GoKawiilOpenSSH Release Notes
OpenSSH 10.5 was released on 2026-08-11. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Recently the OpenSSH team have received a large number of security bug reports, many of which are findings from AI models or made with AI assistance. While many AI reports are determined not to have security impact when considered in the context of a realistic threat model, we very much welcome these reports, especially when combined with human triage, analysis, test-cases and particularly when accompanied by proposed fixes. We have seen a number of cases where a security bug identified by AI tools is subsequently independently discovered by a different researcher. This suggests that adversaries who do not report bugs to OSS projects are likely to be able to discover these bugs too. Given this, the OpenSSH team will, for now, be making more frequent releases to get bugfixes into users' hands more quickly rather than batching them until the next planned release. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Potentially-incompatible changes -------------------------------- * Portable OpenSSH now requires ECC (Elliptic Curve Cryptography) support in libcrypto, including support for the NISTP521 curve. ECC is included in the default build configurations of all versions of all libcrypto implementations currently supported by OpenSSH, including LibreSSL, OpenSSL, BoringSSL and AWS LC. The --without-openssl build configuration is not affected. Changes since OpenSSH 10.4 ========================== This release contains a number of security fixes and small bugfixes. Security ======== * ssh-agent(1): fix an interaction between agent locking and the [email protected] extension that is used to identify forwarded agents. These binding requests were refused when the agent was locked, with the result that operations that were intended to be limited to local use only could be performed remotely, including the ability to add PKCS#11 tokens and make use of keys that had destination restrictions applied. Reported by sn0x-sharma * ssh(1): avoid potential realloc use-after-free in the client if a remote forwarding is added via the local session multiplexing socket while a remote forwarding open request is pending with the server. Report and fix from Brian Mingus of Cognatory * sshd(8): make the authorized_keys "restrict" keyword apply correctly to tunnel forwarding too (which is administratively disabled by default). Reported by Erichen, Institute of Computing Technology, Chinese Academy of Sciences New features ------------ * ssh-keygen(1): add ability to set or clear the touch-required and verify-required flags on FIDO private keys when resetting a private key's passphrase. * ssh(1): tweak ordering of certificates tried during pubkey authentication to prefer FIDO keys that do not require user presence (touch) first, and FIDO keys that require user verification via PIN or biometrics last. This effectively tries low-friction authenticators before higher friction ones. * ssh(1): add a "ssh -Z user@host" mode that prints the keys that will be tried for public key authentication in the order that they will be used. * sshd(8) use setproctitle(3) to identify sshd-session when its acting as a post-authentication monitor. Bugfixes -------- * ssh-keyscan(1): make reading the server banner a non-blocking operation to prevent a stuck server from blocking a many-host keyscan from proceeding. * sshd(8): use sshpkt_fatal() instead of plain fatal() for errors in the packet code as this provides context of the failing peer (address, port, user, etc). * sshd(8): when signing hostkey proofs for a client UpdateHostKeys request, allow each hostkey to perform at most one signature operation. * sshd(8) fix GSSAPI option names, that were broken during a servconf.c refactoring in openssh-10.4; bz3974. * ssh-keygen(1): pass back errors from ed25519 key generation, which theoretically can fail. GHPR702. * sshd(8): move check of public key type against allowed algorithms to before parsing of the key sent by the peer. This removes at least some key parsing and verification paths from the pre-auth attack surface. Suggested by Christopher Paul Rohlf of Anthropic. * ssh-keygen(1): fix double frees (impossible to reach outside of a test harness), and also use freezero where possible. From Christopher Paul Rohlf at Anthropic. * sshd(8): fix ChannelTimeout and RekeyLimit not being applied in sshd_config Match blocks. * sshd(8): in sshd config dump mode, write all directives in mixed case for consistency Portability ----------- * sshd(8): re-allow PAMServiceName inside a Match block, which was incorrectly disabled during a refactoring in openssh-10.4. bz3987 Checksums: ========== - SHA1 (openssh-10.5.tar.gz) = 273163972f623bb9bffef9fd75a85c74d3b22633 - SHA256 (openssh-10.5.tar.gz) = 9Zhp0C/mDWNLmnatq68mtbqOUhvbyYcffH04dsHUwZQ= - SHA1 (openssh-10.5p1.tar.gz) = 3067e2af7c526b31c7e94bc3ed38904ef791eb2c - SHA256 (openssh-10.5p1.tar.gz) = 1E0oqDnqna+WnMaRUP3lmRCys5Nh2tgaO9bL0ZIY2xE= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 10.4 was released on 2026-07-06. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Potentially-incompatible changes -------------------------------- * sshd(8): configuration dump mode ("sshd -G") now writes directives in mixed case (e.g. "PubkeyAuthentication") whereas previously it emitted only lower-case names. * sshd(8): on Linux systems with the seccomp sandbox enabled, failures to enable SECCOMP or NO_NEW_PRIVS are now fatal. Previously sshd(8) would log the error but continue operation, to support systems that lacked these features. Now systems that lack these should instead disable the sandbox at configure time. * ssh(1), sshd(8): make the transport protocol stricter by disconnecting if the peer sends non-KEX messages during a post- authentication key re-exchange. Previously a malicious peer could continue sending non-key exchange messages without penalty. These would be buffered, causing memory to be wasted up until the connection terminated or the server/client hit a memory limit. Implementations that do not restrict messages sent during key exchange as per RFC4253 section 7.1 may be disconnected. Reported by Marko Jevtic. Changes since OpenSSH 10.3 ========================== This release contains a number of security fixes as well as general bugfixes and a couple of new features. Security ======== * sftp(1): when downloading files on the command-line using "sftp host:/path .", a malicious server could cause the file to be downloaded to an unexpected location. This issue was identified by the Swival Security Scanner. * scp(1): when copying files between two remote destinations, do not allow a malicious server to write files to the parent directory of the intended target directory. This issue was identified by the Swival Security Scanner. * sshd(8): when using the "internal-sftp" SFTP server implementation (this is not the default), long command lines were previously truncated silently after the 9th argument. If a security-relevant option was in the 10th or later position, it would be discarded. Reported by Steve Caffrey. * sshd(8): add a documentation note to mention that the GSSAPIStrictAcceptorCheck option is ineffective when the server is joined to a Windows Active Directory. Reported by Yarin Aharoni of Safebreach. * sshd(8): DisableForwarding=yes didn't override PermitTunnel=yes as it was documented to do. Note that PermitTunnel is not enabled by default. Reported independently by Huzaifa Sidhpurwala of Redhat and Marko Jevtic. * sshd(8): avoid a potential pre-authentication denial of service when GSSAPIAuthentication was enabled (this feature is off by default). This was not mitigated by MaxAuthTries, but would be penalised by PerSourcePenalties. This was reported by Manfred Kaiser of the milCERT AT (Austrian Ministry of Defence). * sshd(8): fix a number of cases where the minimum authentication delay was not being enforced. Reported by the Orange Cyberdefense Vulnerability Team. * ssh(1): fix a possible client-side use-after-free if the server changes its host key during a key reexchange. This was reported by Zhenpeng (Leo) Lin of Depthfirst. New features ------------ * All: add experimental support for a composite post-quantum signature scheme that combines ML-DSA 44 and Ed25519 as specified in draft-miller-sshm-mldsa44-ed25519-composite-sigs. This scheme is not enabled by default. To use it, you'll need to add it to HostKeyAlgorithms, PubkeyAcceptedAlgorithms, etc. Keys may be generated using "ssh-keygen -t mldsa44-ed25519". * ssh(1), sshd(8): replace the wildcard pattern matcher with an implementation based on an NFA. This avoids exponential worst-case behaviour for the old implementation. Bugfixes -------- * ssh-agent(1): fix incorrect reply to "query" SSH_AGENTC_EXTENSION requests. bz3967 * sshd(8): avoid sending observably different messages for valid vs invalid users in GSSAPIAuthentication (disabled by default). * ssh(1), sshd(8): fix several bugs that incorrectly classified bulk traffic as interactive. bz3972, bz3958 * ssh-keygen(1), ssh-add(1): skip unsupported key types when downloading resident keys from a FIDO token. Previously, downloads would abort when one was encountered. GHPR657 * ssh(1): fix a potential use-after-free on an error path if cipher_init() fails. * sshd(8): perform stricter encoding and validation of transport state passed between sshd privilege separation subprocesses. This somewhat further hardens the server against attacks on sshd-auth or sshd-session subprocesses. * ssh-agent(1): avoid possible runtime denial of service by enforcing some limits on the length of usernames in key use constraints. * sftp(1): fix two separate one-byte out-of-bounds reads, in SSH2_FXP_REALPATH and batch command processing. * sftp-server(8): disallow use of the copy-data extension to read and write to the same inode simultaneously. * ssh(1), sshd(8): avoid strlen(NULL) crash if an X11 channel was created before the x11-req SSH_MSG_CHANNEL_REQUEST was sent. GHPR679 * sftp(1), scp(1): avoid a situation where sftp_download() could get stuck in a loop if a broken server repeatedly returned zero length while reading a file. * ssh(1): avoid leaking DNS0x20 case-randomised names into names canonicalised using CanonicalizePermittedCNAMEs. bz3966 * sftp-server(8): avoid truncation of pathnames passed to lstat() during SSH_FXP_REALPATH handling on systems where PATH_MAX is not the actual max. GHPR688 * ssh(1), sshd(8): correct arming of poll(2) event masks for some socket-type channels. GHPR660 * sshd(8): major refactor of sshd_config parsing and management code, to allow for more exact serialisation/deserialisation across privilege separation boundaries. * ssh-add(1): open connection to the agent only after getopt() processing has completed, to give options like "-v" a chance to display debug information about this operation. * crypto code: fix bounds checking when signing messages of length greater than will fit in a size_t. In OpenSSH, message sizes are bounded by SSHBUF_SIZE_MAX so this was unreachable. * crypto code: add signature malleability and pubkey validity checks to ed25519 verification. SSH doesn't depend on these properties * crypto code: fix ECDSA order check for curves with cofactor != 1. All supported EC curves have cofactor 1, so this was unreachable. * sshd(8): differentiate between execution failures and a subsystem that was not found when logging why a subsystem failed to start. GHPR637 * All: use safer idioms for timegm(3) and mktime(3) error detection. * ssh(1), sshd(8): avoid accepting invalid cipher or MAC lists in config files or command-line arguments. This could cause runtime failures later. * ssh(1): fix NULL deref crash during pubkey auth when using a PEM style private key with no corresponding .pub key adjacent to it. * sshd(8): don't print an error message when trying to load a host private key when PKCS#11 keys are in use, as these don't need the private half on the filesystem. GHPR664 * All: don't use deprecated ERR_load_crypto_strings(). GHPR650 * ssh(1): properly report errors during configuration default setting. GHPR649 * ssh(1): use correct directive name (Match instead of Host) in error message. bz3968 * sftp(1): fix "ls -ln" which was not correctly showing numeric UID/GIDs but rather user and group names. bz3953 * sshd(8): avoid possible NULL dereference if an allocation fails during config parsing. bz3948 * All: fix ineffective guards against loading overly large public keys in several places. bz3969 and bz3970 * sftp(1): ensure file descriptors used by sftp to communicate to its ssh(1) subprocess don't leak into executed subprocesses (e.g. via "!"). GHPR693 Portability ----------- * Sync fmt_scaled.c with OpenBSD upstream, picking up an exactness fix for large exponents (GHPR671) * sshd(8): remove duplicate sandbox entry for clock_gettime64. * ssh(1), sshd(8): use correct IPTOS_DSCP_VA value if not provided by the system headers. * Sync getrrsetbyname.c with OpenBSD upstream, picking up robustness fixes. * Disable replacements in openbsd-compat for strvisx(3) and stravis(3), as these are unused in OpenSSH * Avoid fortify warnings on Android bz3954 * Fix a number of memory leaks on error paths in the portability code. GHPR681 * Revise the README.privsep documentation to reflect sshd's recent switch to a multi-binary model. Checksums: ========== - SHA1 (openssh-10.4.tar.gz) = 8502b516230865e229d55045bb4ccc67aeae905b - SHA256 (openssh-10.4.tar.gz) = qUVI+wMg4mVpiQbXvfMVkF3Zuyy2JrS+ZjN764mtyGE= - SHA1 (openssh-10.4p1.tar.gz) = ae8650a71cc52dbbd049519cee276ae6d65c2c4d - SHA256 (openssh-10.4p1.tar.gz) = 72Am3SrqjVYFljjV0yYpAsiSzrqfiDlYNeDQbT+2Mjg= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 10.3 was released on 2026-04-02. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Potentially-incompatible changes -------------------------------- * ssh(1), sshd(8): remove bug compatibility for implementations that don't support rekeying. If such an implementation tries to interoperate with OpenSSH, it will now eventually fail when the transport needs rekeying. * sshd(8): prior to this release, a certificate that had an empty principals section would be treated as matching any principal (i.e. as a wildcard) when used via authorized_keys principals="" option. This was intentional, but created a surprising and potentially risky situation if a CA accidentally issued a certificate with an empty principals section: instead of being useless as one might expect, it could be used to authenticate as any user who trusted the CA via authorized_keys. [Note that this condition did not apply to CAs trusted via the sshd_config(5) TrustedUserCAKeys option.] This release treats an empty principals section as never matching any principal, and also fixes interpretation of wildcard characters in certificate principals. Now they are consistently implemented for host certificates and not supported for user certificates. * ssh(1): the -J and equivalent -oProxyJump="..." options now validate user and host names for ProxyJump/-J options passed via the command-line (no such validation is performed for this option in configuration files). This prevents shell injection in situations where these were directly exposed to adversarial input, which would have been a terrible idea to begin with. Reported by rabbit. Changes since OpenSSH 10.2 ========================== This release contains some relatively minor security fixes as well as a number of feature improvements and general bugfixes. Security ======== * ssh(1): validation of shell metacharacters in user names supplied on the command-line was performed too late to prevent some situations where they could be expanded from %-tokens in ssh_config. For certain configurations, such as those that use a "%u" token in a "Match exec" block, an attacker who can control the user name passed to ssh(1) could potentially execute arbitrary shell commands. Reported by Florian Kohnhäuser. We continue to recommend against directly exposing ssh(1) and other tools' command-lines to untrusted input. Mitigations such as this can not be absolute given the variety of shells and user configurations in use. * sshd(8): when matching an authorized_keys principals="" option against a list of principals in a certificate, an incorrect algorithm was used that could allow inappropriate matching in cases where a principal name in the certificate contains a comma character. Exploitation of the condition requires an authorized_keys principals="" option that lists more than one principal *and* a CA that will issue a certificate that encodes more than one of these principal names separated by a comma (typical CAs strongly constrain which principal names they will place in a certificate). This condition only applies to user- trusted CA keys in authorized_keys, the main certificate authentication path (TrustedUserCAKeys/AuthorizedPrincipalsFile) is not affected. Reported by Vladimir Tokarev. * scp(1): when downloading files as root in legacy (-O) mode and without the -p (preserve modes) flag set, scp did not clear setuid/setgid bits from downloaded files as one might typically expect. This bug dates back to the original Berkeley rcp program. Reported by Christos Papakonstantinou of Cantina and Spearbit. * sshd(8): fix incomplete application of PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms with regard to ECDSA keys. Previously if one of these directives contains any ECDSA algorithm name (say "ecdsa-sha2-nistp384"), then any other ECDSA algorithm would be accepted in its place regardless of whether it was listed or not. Reported by Christos Papakonstantinou of Cantina and Spearbit. * ssh(1): connection multiplexing confirmation (requested using "ControlMaster ask/autoask") was not being tested for proxy mode multiplexing sessions (i.e. "ssh -O proxy ..."). Reported by Michalis Vasileiadis. New features ------------ * ssh(1), sshd(8): support IANA-assigned codepoints for SSH agent forwarding, as per draft-ietf-sshm-ssh-agent. Support for the new names is advertised via the EXT_INFO message. If a server offers support for the new names, then they are used preferentially. Support for the pre-standardisation "@openssh.com" extensions for agent forwarding remains supported. * ssh-agent(1): implement support for draft-ietf-sshm-ssh-agent "query" extension. * ssh-add(1): support querying the protocol extensions via the agent "query" extension with a new -Q flag. * ssh(1): support multiple files in a ssh_config RevokedHostKeys directive. bz3918 * sshd(8): support multiple files in a sshd_config RevokedKeys directive bz3918 * ssh(1): add a ~I escape option that shows information about the current SSH connection. * ssh(1): add an "ssh -Oconninfo user@host" multiplexing command that shows connection information, similar to the ~I escapechar. * ssh(1): add an "ssh -O channels user@host" multiplexing command to get a running mux process to show information about what channels are currently open. * sshd(8): add 'invaliduser' penalty to PerSourcePenalties, which is applied to login attempts for usernames that do not match real accounts. Defaults to 5s to match 'authfail' but allows administrators to block such attempts for longer if desired. * sshd(8): add a GSSAPIDelegateCredentials option for the server, controlling whether it accepts delegated credentials offered by the client. This option mirrors the same option in ssh_config. GHPR614 * ssh(1), sshd(8): support the VA DSCP codepoint in the IPQoS directive. * sshd(8): convert PerSourcePenalties to using floating point time, allowing penalties to be less than a second. This is useful if you need to penalise things you expect to occur at >=1 QPS. * ssh-keygen(1): support writing ED25519 keys in PKCS8 format. GHPR570 * Support the ed25519 signature scheme via libcrypto. Bugfixes -------- * sshd(8): make IPQoS first-match-wins in sshd_config, like other configuration directives. bz3924 * sshd(8): fix potential crash when MaxStartups is using a single argument (i.e. not using the MaxStartps x:y:z form) to a value below 10. bz3941 * sshd(8): fix a potential hang during key exchange if needed DH group values were missing from /etc/moduli. * ssh-agent(1): fix return values from extensions to be correct wrt draft-ietf-sshm-ssh-agent: extension requests should indicate failure using SSH_AGENT_EXTENSION_FAILURE rather than the generic SSH_AGENT_FAILURE error code. This allows the client to discern between "the request failed" and "the agent doesn't support this extension". * ssh(1): use fmprintf for showing challenge-response name and info to preserve UTF-8 characters where appropriate. Prompted by GitHub PR#452. * scp(1): when uploading a directory using sftp/sftp (e.g. during a recursive transfer), don't clobber the remote directory permissions unless either we created the directory during the transfer or the -p flag was set. bz3925 * All: implement missing pieces of FIDO/webauthn signature support, mostly related to certificate handling and enable acceptance of this signature format by default. bz3748 GHPR624 GHPR625 * sshd_config(5): make it clear that DenyUsers/DenyGroups overrides AllowUsers/AllowGroups. Previously we specified the order in which the directives are processed but it was ambiguous as to what happened if both matched. * ssh(1): don't try to match certificates held in an agent to private keys. This matching is done to support certificates that were loaded without their private key material, but is unnecessary for agent-hosted certificate which always have private key material available in the agent. Worse, this matching would mess up the request sent to the agent in such a way as to break usage of these keys when the key usage was restricted in the agent. bz3752 * sftp(1): if editline has been switched to vi mode (i.e. via "bind -v" in .editrc), setup a keybinding so that command mode can be entered. * ssh(1), sshd(8): improve performance of keying the sntrup761 key agreement algorithm. * ssh(1), sshd(8): enforce maximum packet/block limit during pre-authentication phase. * sftp(1): don't misuse the sftp limits extension's open-handles field. This value is supposed to be the number of handles a server will allow to be opened and not a number of outstanding read/write requests that can be sent during an upload/download. * sshd(8): don't crash at connection time if the main sshd_config lacks any subsystem directive but one is defined in a Match block. bz3906 * sshd_config(5): add a warning next to the ForceCommand directive that forcing a command doesn't automatically disable forwarding. * sshd_config(5): add a warning that TOKENS are replaced without filtering or escaping and that it's the administrator's responsibility to ensure they are used safely in context. * scp(1): correctly quote filenames in verbose output for local-> local copies. bz3900 * sshd(8): don't mess up the PerSourceNetBlockSize IPv6 mask if sscanf didn't decode it. GHPR598 * ssh-add(1): when loading FIDO2 resident keys, set the comment to the FIDO application string. This matches the behaviour of ssh-keygen -K. GHPR608 * sshd(8): don't strnvis() log messages that are going to be logged by sshd-auth via its parent sshd-session process, as the parent will also run them though strnvis(). Prevents double-escaping of non-printing characters in some log messages. bz3896 * ssh-agent(1): escape SSH_AUTH_SOCK paths that are sent to the shell as setenv commands. Unbreaks ssh-agent for home directory paths that contain whitespace. bz3884 * All: Remove unnecessary checks for ECDSA public key validity. * sshd(8): activate UnusedConnectionTimeout only after the last channel has closed. Previously UnusedConnectionTimeout could fire early after a ChannelTimeout. This was not a problem for the OpenSSH client because it terminates once all channels have closed but could cause problems for other clients (e.g. API clients) that do things differently. bz3827 * All: fix PKCS#11 key PIN entry problems introduced in openssh-10.1/10.2. bz3879 * scp(1): when using the SFTP protocol for transfers, fix implicit destination path selection when source path ends with "..". bz3871 * sftp(1): when tab-completing a filename, ensure that the completed string does not end up mid-way through a multibyte character, as this will cause a fatal() later on. GHPR#587 * ssh-keygen(1): fix crash at exit (visible via ssh-keygen -D) when multiple keys loaded. * scp(1)/sftp(1): correctly display bandwidths >2GBps in the progress meter. Portability ----------- * sshd(8): fix condition introduced in openssh 10.2p1 stable branch here a PAM module that changed the requested username between SSH_MSG_USERAUTH_REQUEST messages during authentication could confuse the PAM stack and let it proceed with a different understanding of the active username than the rest of sshd. Reported by Mike Damm. * sshd(8): immediately report interactive instructions to clients when using keyboard-interactive authentication with PAM. bz2876 * sshd(8): fix duplicate PAM messages under some situations. * sshd(8): don't leak PAM handle on repeat invocations. bz3882 * All: support linking libcrypto implementations (e.g. BoringSSL) that require libstdc++. * sshd(8): fix ut_type for btmp records, correctly using LOGIN_PROCESS and USER_PROCESS. * sshd(8): allow uname(3) in the seccomp sandbox. This is needed by zlib-ng on RISC-V platforms. * All: remove remaining OpenSSL_add_all_algorithms() calls. We already have OPENSSL_init_crypto() in the compat layer. Prompted by github PR#606 * All: fix builds on older Mac OS wrt nfds_t. * mdoc2man: several improvements including better support for Dl and Ns inside Ic. Checksums: ========== - SHA1 (openssh-10.3.tar.gz) = 854863c04cd28242d73ac6c3ee9c37fa756f1a2f - SHA256 (openssh-10.3.tar.gz) = aCU5P47rM+m4N8/i2JOHMOMhafMYqBhvQQSnPXczN5M= - SHA1 (openssh-10.3p1.tar.gz) = 9c78838ec07af14aff54f3755ac56ce6812452a9 - SHA256 (openssh-10.3p1.tar.gz) = VmgqNruS3PS08Bb9jsjnQFm3mo3iXBXWcNcx59GORfQ= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 10.2 was released on 2025-10-10. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Future deprecation warning -------------------------- * A future release of OpenSSH will deprecate support for SHA1 SSHFP records due to weaknesses in the SHA1 hash function. SHA1 SSHFP DNS records will be ignored and ssh-keygen -r will generate only SHA256 SSHFP records. The SHA256 hash algorithm, which has no known weaknesses, has been supported for SSHFP records since OpenSSH 6.1, released in 2012. Changes since OpenSSH 10.1 ========================== This is a bugfix release, primarily to fix a problem that rendered ssh(1) unusable when ControlPersist was enabled. Bugfixes -------- * ssh(1): fix mishandling of terminal connections when ControlPersist was active that rendered the session unusable. bz3872 * ssh-keygen(1): fix download of keys from PKCS#11 tokens. * ssh-keygen(1): fix CA signing operations when the CA key is held in a ssh-agent(1). bz3877 Portability ----------- * All: support platforms without mmap(2), e.g. WASM builds such as https://hterm.org * All: fix builds on FreeBSD for missing fnctl.h include. * All: fix builds on MacOS <10.12 Sierra, which lacks clock_gettime(3) * sshd(8): don't PAM_RHOST if the remote host is the "UNKNOWN" placeholder name. Avoids potential hangs in some PAM modules as they try to resolve it. Note, sshd(8) only uses the "UNKNOWN" name when the connection is not on an IPv4 or IPv6 socket. Checksums: ========== SHA1 (openssh-10.2.tar.gz) = 6fcda8004bad0fb0eaee60e8308f91b605ad0dce SHA256 (openssh-10.2.tar.gz) = y0rCEdrVc4OJRZLg0u3F0frAgz87ydeTktCk3rQfVj8= SHA1 (openssh-10.2p1.tar.gz) = c34efade16109f065ec8c834f237bcedd8d7ef5c SHA256 (openssh-10.2p1.tar.gz) = zMQsBBmTeVkmP6Hb0W2vwYxWuYTANWLSk3zlamD3mLI= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 10.1 was released on 2025-10-06. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Future deprecation warning -------------------------- * A future release of OpenSSH will deprecate support for SHA1 SSHFP records due to weaknesses in the SHA1 hash function. SHA1 SSHFP DNS records will be ignored and ssh-keygen -r will generate only SHA256 SSHFP records. The SHA256 hash algorithm, which has no known weaknesses, has been supported for SSHFP records since OpenSSH 6.1, released in 2012. Potentially-incompatible changes -------------------------------- * ssh(1): add a warning when the connection negotiates a non-post quantum key agreement algorithm. This warning has been added due to the risk of "store now, decrypt later" attacks. More details at https://openssh.com/pq.html This warning may be controlled via a new WarnWeakCrypto ssh_config option, defaulting to on. This option is likely to control additional weak crypto warnings in the future. * ssh(1), sshd(8): major changes to handling of DSCP marking/IPQoS In both client and server the default DSCP (a.k.a IPQoS) values were revised and the way these values are used during runtime has changed. Interactive traffic is now assigned to the EF (Expedited Forwarding) class by default. This provides more appropriate packet prioritisation information for the intermediate network, such as wireless media (cf. RFC 8325). Non-interactive traffic will now use the operating system default DSCP marking. Both the interactive and non-interactive DSCP values may be overridden via the IPQoS keyword, described in ssh_config(5) and sshd_config(5). The appropriate DSCP marking is now automatically selected and updated as needed over the course of a connection's lifetime. ssh(1) and sshd(8) will switch between the interactive and non-interactive IPQoS values depending on the type of SSH channels open at the time. For example, if an sftp session is using the connection alongside a shell session, then the non- interactive value will be used for the duration of the sftp. A connection which contains only interactive sessions is marked EF. * ssh(1), sshd(8): deprecate support for IPv4 type-of-service (ToS) keywords in the IPQoS configuration directive. Type of Service (ToS) was deprecated in the late nineties and replaced with the Differentiated Services architecture, which has significant advantages for operators because it offers more granularity. OpenSSH switched its default IPQoS from ToS to DSCP values in 2018 (openssh-7.7). IPQoS configurations with 'lowdelay', 'reliability', or 'throughput' will be ignored and will instead use the system default QoS settings. Additionally, a debug message will be logged about the deprecation with a suggestion to use DSCP QoS instead. * ssh-add(1): when adding certificates to an agent, set the expiry to the certificate expiry time plus a short (5 min) grace period. This will cause the agent to automatically remove certificates shortly after they expire. A new ssh-add -N option disables this behaviour. * All: remove experimental support for XMSS keys. This was never enabled by default. We expect to implement a new post-quantum signature scheme in the near future. * ssh-agent(1), sshd(8): move agent listener sockets from /tmp to under ~/.ssh/agent for both ssh-agent(1) and forwarded sockets in sshd(8). This ensures processes that have restricted filesystem access that includes /tmp do not ambiently have the ability to use keys in an agent. Moving the default directory has the consequence that the OS will no longer clean up stale agent sockets, so ssh-agent now gains this ability. To support $HOME on NFS, the socket path includes a truncated hash of the hostname. ssh-agent will, by default, only clean up sockets from the same hostname. ssh-agent(1) gains some new flags: -U suppresses the automatic cleanup of stale sockets when it starts. -u forces a cleanup without keeping a running agent, -uu forces a cleanup that ignores the hostname. -T makes ssh-agent put the socket back in /tmp. Changes since OpenSSH 10.0 ========================== This release contains a minor security fix as well as a number of feature improvements and bugfixes. Security ======== * ssh(1): disallow control characters in usernames passed via the commandline or expanded using %-sequences from the configuration file, and disallow \0 characters in ssh:// URIs. If an ssh(1) commandline was constructed using usernames or URIs obtained from an untrusted source, and if a ProxyCommand that uses the %r expansion was configured, then it may be possible for an attacker to inject shell expressions that may be executed when the proxy command is started. We strongly recommend against using untrusted inputs to construct ssh(1) commandlines. This change also relaxes the validity checks in one small way: usernames supplied via the configuration file as literals (i.e. that have no % expansion characters) are not subject to these validity checks. This allows usernames that contain arbitrary characters to be used, but only via configuration files. This is done on the basis that ssh's configuration is trusted. This issue was reported by David Leadbeater. New features ------------ * ssh(1), sshd(8): add SIGINFO handlers to log active channel and session information. * sshd(8): when refusing a certificate for user authentication, log enough information to identify the certificate in addition to the reason why it was being denied. Makes debugging certificate authorisation problems a bit easier. * ssh(1), ssh-agent(1): support ed25519 keys hosted on PKCS#11 tokens. * ssh(1): add an ssh_config(5) RefuseConnection option that, when encountered while processing an active section in a configuration, terminates ssh(1) with an error message that contains the argument to the option. This may be useful for expressing reminders or warnings in config files, for example: Match host foo RefuseConnection "foo is deprecated, use splork instead" * sshd(8): make the X11 display number check relative to X11DisplayOffset. This will allow people to use X11DisplayOffset to configure much higher port ranges if they really want, while not changing the default behaviour. * unit tests: the unit test framework now includes some basic benchmarking capabilities. Run with "make UNITTEST_BENCHMARK=yes" on OpenBSD or "make unit-bench" on Portable OpenSSH. Bugfixes -------- * sshd(8): fix mistracking of MaxStartups process exits in some situations. At worst, this could cause all MaxStartups slots to fill and sshd to refuse new connections. * ssh(1): fix delay on X client startup when ObscureKeystrokeTiming is enabled. bz#3820 * sshd(8): increase the maximum size of the supported configuration from 256KB to 4MB, which ought to be enough for anybody. Fail early and visibly when this limit is breached. bz3808 * sftp(1): during sftp uploads, avoid a condition where a failed write could be ignored if a subsequent write succeeded. This is unlikely but technically possible because sftp servers are allowed to reorder requests. * sshd(8): avoid a race condition when the sshd-auth process exits that could cause a spurious error message to be logged. * sshd(8): log at level INFO when PerSourcePenalties actually blocks access to a source address range. Previously this was logged at level VERBOSE, which hid enforcement actions under default config settings. * sshd(8): GssStrictAcceptor was missing from sshd -T output; fix * sshd(8): Make the MaxStartups and PerSourceNetBlockSize options first-match-wins as advertised. bz3859 * ssh(1): fix an incorrect return value check in the local forward cancellation path that would cause failed cancellations not to be logged. * sshd(8): make "Match !final" not trigger a second parsing pass of ssh_config (unless hostname canonicalisation or a separate "Match final" does). bz3843 * ssh(1): better debug diagnostics when loading keys. Will now list key fingerprint and algorithm (not just algorithm number) as well as making it explicit which keys didn't load. * All: fix a number of memory leaks found by LeakSanitizer, Coverity and manual inspection. * sshd(8): Output the current name for PermitRootLogin's "prohibit-password" in sshd -T instead of its deprecated alias "without-password". bz#3788 * ssh(1): make writing known_hosts lines more atomic by writing the entire line in one operation and using unbuffered stdio. Usually writes to this file are serialised on the "Are you sure you want to continue connecting?" prompt, but if host key checking is disabled and connections were being made with high concurrency then interleaved writes might have been possible. Portability ----------- * sshd(8): check the username didn't change during the PAM transactions. PAM modules can change the user during their execution, but this is not supported by sshd(8). If such a case was incorrectly configured by the system administrator, then sshd(8) could end up using a different username to the one authorised by PAM. * sshd(8): don't log audit messages with UNKNOWN hostname to avoid slow DNS lookups in the audit subsystem. * All: when making a copy of struct passwd, ensure struct fields are non-NULL. Android libc can return NULL pw_gecos, for example. * All: Remove status bits from OpenSSL >=3 version check. * sshd(8), ssh(1): Use SSH_TUN_COMPAT_AF on FreeBSD. Otherwise tun forwarding from other OSes fails as soon as the first IPv6 message is sent by the other side (which is usually a Router Solicitation ICMPv6 message which is sent as soon as the interface is up). * ssh(1), ssh-agent(8): check for nlist function presence before attempting to use it instead of relying on the presence of the nlist.h header. Mac OS X, for example, has the header but not the function in the 64bit libraries. * All: fill in missing system header files. Create replacement header files inside openbsd-compat for common headers that are missing on a given platform. Usually these are just empty, but in some cases they'll include the equivalent file. This avoids having to wrap those includes in '#ifdef HAVE_FOO_H' and reduces the diff between Portable OpenSSH and OpenBSD. * sshd(8): handle futex_time64 properly in seccomp sandbox Previously we only allowed __NR_futex, but some 32-bit systems apparently support __NR_futex_time64. We had support for this in the sandbox, but because of a macro error only __NR_futex was allowlisted. * Add contrib/gnome-ssh-askpass4 for GNOME 40+ using the GCR API. * sshd(8): let ga_init() fail gracefully if getgrouplist does. Apparently getgrouplist() can fail on OSX when passed a non-existent group name. Other platforms seem to return a group list consisting of the numeric gid passed to the function. bz3848 * ssh-agent(1): exit 0 from SIGTERM under systemd socket-activation, preventing a graceful shutdown of an agent via systemd from incorrectly marking the service as "failed". * build: wrap some autoconf macros in AC_CACHE_CHECK. This allows skipping/overriding the OSSH_CHECK_CFLAG_COMPILE and OSSH_CHECK_CFLAG_LINK macros used to discover supported compiler or linker flags. E.g. $ ./configure ossh_cv_cflag__fzero_call_used_regs_used=no [...] checking if cc supports compile flag -fzero-call-used-regs=used and linking succeeds... (cached) no Checksums: ========== SHA1 (openssh-10.1.tar.gz) = 8eef44a945a9a9a5a99213ab0d57e35b7ba60e75 SHA256 (openssh-10.1.tar.gz) = j9ymvhvdGMeAvh1oTI2YmOAwv7Ao70gbGPyPedgQsBU= SHA1 (openssh-10.1p1.tar.gz) = 7fd17b99d1beffb47cd380d64079e920bb0bd91f SHA256 (openssh-10.1p1.tar.gz) = ufx6K4JXlGem8vQ+SoHI4d/aYU3bT5slWq/XAgu/B1g= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 10.0 was released on 2025-04-09. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Potentially-incompatible changes -------------------------------- * This release removes support for the weak DSA signature algorithm, completing the deprecation process that began in 2015 (when DSA was disabled by default) and repeatedly warned over the last 12 months. * scp(1), sftp(1): pass "ControlMaster no" to ssh when invoked by scp & sftp. This disables implicit session creation by these tools when ControlMaster was set to yes/auto by configuration, which some users found surprising. This change will not prevent scp/sftp from using an existing multiplexing session if one had already been created. GHPR557 * This release has the version number 10.0 and announces itself as "SSH-2.0-OpenSSH_10.0". Software that naively matches versions using patterns like "OpenSSH_1*" may be confused by this. * sshd(8): this release removes the code responsible for the user authentication phase of the protocol from the per- connection sshd-session binary to a new sshd-auth binary. Splitting this code into a separate binary ensures that the crucial pre-authentication attack surface has an entirely disjoint address space from the code used for the rest of the connection. It also yields a small runtime memory saving as the authentication code will be unloaded after the authentication phase completes. This change should be largely invisible to users, though some log messages may now come from "sshd-auth" instead of "sshd-session". Downstream distributors of OpenSSH will need to package the sshd-auth binary. * sshd(8): this release disables finite field (a.k.a modp) Diffie-Hellman key exchange in sshd by default. Specifically, this removes the "diffie-hellman-group*" and "diffie-hellman-group-exchange-*" methods from the default KEXAlgorithms list. The client is unchanged and continues to support these methods by default. Finite field Diffie Hellman is slow and computationally expensive for the same security level as Elliptic Curve DH or PQ key agreement while offering no redeeming advantages. ECDH has been specified for the SSH protocol for 15 years and some form of ECDH has been the default key exchange in OpenSSH for the last 14 years. * sshd(8): this release removes the implicit fallback to compiled- in groups for Diffie-Hellman Group Exchange KEX when the moduli file exists but does not contain moduli within the client- requested range. The fallback behaviour remains for the case where the moduli file does not exist at all. This allows administrators more explicit control over which DH groups will be selected, but can lead to connection failures if the moduli file is edited incorrectly. bz#2793 Changes since OpenSSH 9.9 ========================= This release contains a minor security fix as well as a number of feature improvements and bugfixes. Security ======== * sshd(8): fix the DisableForwarding directive, which was failing to disable X11 forwarding and agent forwarding as documented. X11 forwarding is disabled by default in the server and agent forwarding is off by default in the client. New features ------------ * ssh(1): the hybrid post-quantum algorithm mlkem768x25519-sha256 is now used by default for key agreement. This algorithm is considered to be safe against attack by quantum computers, is guaranteed to be no less strong than the popular curve25519-sha256 algorithm, has been standardised by NIST and is considerably faster than the previous default. * ssh(1): prefer AES-GCM to AES-CTR mode when selecting a cipher for the connection. The default cipher preference list is now Chacha20/Poly1305, AES-GCM (128/256) followed by AES-CTR (128/192/256). * ssh(1): add %-token and environment variable expansion to the ssh_config SetEnv directive. * ssh(1): allow %-token and environment variable expansion in the ssh_config User directive, with the exception of %r and %C which would be self-referential. bz#3477 * ssh(1), sshd(8): add "Match version" support to ssh_config and sshd_config. Allows matching on the local version of OpenSSH, e.g. "Match version OpenSSH_10.*". * ssh(1): add support for "Match sessiontype" to ssh_config. Allows matching on the type of session initially requested, either "shell" for interactive sessions, "exec" for command execution sessions, "subsystem" for subsystem requests, such as sftp, or "none" for transport/forwarding-only sessions. * ssh(1): add support for "Match command ..." support to ssh_config, allowing matching on the remote command as specified on the command-line. * ssh(1): allow 'Match tagged ""' and 'Match command ""' to match empty tag and command values respectively. * sshd(8): allow glob(3) patterns to be used in sshd_config AuthorizedKeysFile and AuthorizedPrincipalsFile directives. bz2755 * sshd(1): support the VersionAddendum in the client, mirroring the option of the same name in the server; bz2745 * ssh-agent(1): the agent will now delete all loaded keys when signaled with SIGUSR1. This allows deletion of keys without having access to $SSH_AUTH_SOCK. * Portable OpenSSH, ssh-agent(1): support systemd-style socket activation in ssh-agent using the LISTEN_PID/LISTEN_FDS mechanism. Activated when these environment variables are set, the agent is started with the -d or -D option and no socket path is set. GHPR502 * ssh-keygen(1): support FIDO tokens that return no attestation data, e.g. recent WinHello. GHPR542 * ssh-agent(1): add a "-Owebsafe-allow=..." option to allow the default FIDO application ID allow-list to be overridden. * Add a work-in-progress tool to verify FIDO attestation blobs that ssh-keygen can optionally write when enrolling FIDO keys. This tool is available under regress/misc/ssh-verify-attestation for experimentation but is not installed by "make install". * ssh-keygen(1): allow "-" as output file for moduli screening. GHPR393 Bugfixes -------- * sshd(8): remove assumption that the sshd_config and any configs it includes can fit in a (possibly enlarged) socket buffer. Previously it was possible to create a sufficiently large configuration that could cause sshd to fail to accept any connection. sshd(8) will now actively manage sending its config to the sshd-session sub-process. * ssh(1): don't start the ObscureKeystrokeTiming mitigations if there has been traffic on a X11 forwarding channel recently. Should fix X11 forwarding performance problems when this setting is enabled. bz3655 * ssh(1): prohibit the comma character in hostnames accepted, but allow an underscore as the first character in a hostname. * sftp(1): set high-water when resuming a "put". Prevents bogus "server reordered acks" debug message. * ssh(1), sshd(8): fix regression in openssh-9.8, which would fail to accept "Match criteria=argument" as well as the documented "Match criteria argument" syntax in ssh_config and sshd_config. bz3739 * sftp(1), ssh(1): fix a number possible NULL dereference bugs, including Coverity CIDs 405019 and 477813. * sshd(8): fix PerSourcePenalty incorrectly using "crash" penalty when LoginGraceTime was exceeded. bz3797 * sshd(8): fix "Match invalid-user" from incorrectly being activated in initial configuration pass when no other predicates were present on the match line * sshd(8): fix debug logging of user specific delay. GHPR#552 * sshd(8): improve debug logging across sub-process boundaries. Previously some log messages were lost early in the sshd-auth and sshd-session processes' life. * ssh(1): require control-escape character sequences passed via the '-e ^x' command-line to be exactly two characters long. Avoids one byte out-of-bounds read if ssh is invoked as "ssh -e^ ..." GHPR368 * ssh(1), sshd(8): prevent integer overflow in x11 port handling. These are theoretically possible if the admin misconfigured X11DisplayOffset or the user misconfigures their own $DISPLAY, but don't happen in normal operation. bz#3730 * ssh-keygen(1): don't mess up ssh-keygen -l output when the file contains CR characters; GHPR236 bz3385. * sshd(8): add rate limits to logging of connections dropped by PerSourcePenalties. Previously these could be noisy in logs. * ssh(1): fix argument of "Compression" directive in ssh -G config dump, which regressed in openssh-9.8. * sshd(8): fix a corner-case triggered by UpdateHostKeys when sshd refuses to accept the signature returned by an agent holding host keys during the hostkey rotation sub-protocol. This situation could occur in situations where a PKCS#11 smartcard that lacked support for particular signature algorithms was used to store host keys. * ssh-keygen(1): when using RSA keys to sign messages with "ssh-keygen -Y", select the signature algorithm based on the requested hash algorithm ("-Ohashalg=xxx"). This allows using something other than the default of rsa-sha2-512, which may not be supported on all signing backends, e.g. some smartcards only support SHA256. * ssh(1), sshd(8), ssh-keyscan(1): fix ML-KEM768x25519 KEX on big-endian systems. * Many regression and interop test improvements. Portability ----------- * All: add support for AWS-LC (AWS libcrypto). bz3784 * sshd(8): add wtmpdb support as a Y2038 safe wtmp replacement. * sshd(8): add support for locking sshd into memory, enabled with the --with-linux-memlock-onfault configure flag. * Add support for building a standalone sk-libfido2 library, enabled by --with-security-key-standalone * ssh(1), sshd(8), ssh-keyscan(1): include __builtin_popcount replacement function. for compilers that lack it. * All: Check for and replace le32toh, le64toh, htole64 separately. It appears that at least some versions of endian.h in glibc do not have the latter two. bz#3794 * Remove ancient RHL 6.x config in RPM spec. Checksums: ========== - SHA1 (openssh-10.0.tar.gz) = 933f4fded0497ef6a588381257276e156a70f9c3 - SHA256 (openssh-10.0.tar.gz) = oaJ+cXLCVoCZAz9W5W1vF7ko4GJW6iq7JmblrPUA34Q= - SHA1 (openssh-10.0p2.tar.gz) = ac4205e827aea383bf316a33a0e2d5b66b85fcf8 - SHA256 (openssh-10.0p2.tar.gz) = AhoucJoO30JQsSVr1anlAEEakN3avqgw7VnO+Q652Fw= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 9.9p2 was released on 2025-02-18. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Changes since OpenSSH 9.9p1 =========================== This release fixes two security bugs. Security ======== * Fix CVE-2025-26465 - ssh(1) in OpenSSH versions 6.8p1 to 9.9p1 (inclusive) contained a logic error that allowed an on-path attacker (a.k.a MITM) to impersonate any server when the VerifyHostKeyDNS option is enabled. This option is off by default. * Fix CVE-2025-26466 - sshd(8) in OpenSSH versions 9.5p1 to 9.9p1 (inclusive) is vulnerable to a memory/CPU denial-of-service related to the handling of SSH2_MSG_PING packets. This condition may be mitigated using the existing PerSourcePenalties feature. Both vulnerabilities were discovered and demonstrated to be exploitable by the Qualys Security Advisory team. We thank them for their detailed review of OpenSSH. For OpenBSD, fixes to these problems are available as errata; refer to https://www.openbsd.org/errata.html Bugfixes ======== * ssh(1), sshd(8): fix regression in Match directive that caused failures when predicates and their arguments were separated by '=' characters instead of whitespace (bz3739). * sshd(8): fix the "Match invalid-user" predicate, which was matching incorrectly in the initial pass of config evaluation. * ssh(1), sshd(8), ssh-keyscan(1): fix mlkem768x25519-sha256 key exchange on big-endian systems. * Fix a number of build problems on particular operating systems / configurations. Checksums: ========== - SHA1 (openssh-9.9p2.tar.gz) = edefe960645780dee78059c444d4261667ad3056 - SHA256 (openssh-9.9p2.tar.gz) = karbYD4IzChe3fll4RmdAlhfqU2ZTWyuW0Hhch4hVnM= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 9.9 was released on 2024-09-19. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Future deprecation notice ========================= OpenSSH plans to remove support for the DSA signature algorithm in early 2025. This release disables DSA by default at compile time. DSA, as specified in the SSHv2 protocol, is inherently weak - being limited to a 160 bit private key and use of the SHA1 digest. Its estimated security level is only 80 bits symmetric equivalent. OpenSSH has disabled DSA keys by default since 2015 but has retained run-time optional support for them. DSA was the only mandatory-to- implement algorithm in the SSHv2 RFCs, mostly because alternative algorithms were encumbered by patents when the SSHv2 protocol was specified. This has not been the case for decades at this point and better algorithms are well supported by all actively-maintained SSH implementations. We do not consider the costs of maintaining DSA in OpenSSH to be justified and hope that removing it from OpenSSH can accelerate its wider deprecation in supporting cryptography libraries. Currently DSA is disabled at compile time. The final step of removing DSA support entirely is planned for the first OpenSSH release of 2025. DSA support may be re-enabled on OpenBSD by setting "DSAKEY=yes" in Makefile.inc. To enable DSA support in portable OpenSSH, pass the "--enable-dsa-keys" option to configure. Potentially-incompatible changes -------------------------------- * ssh(1): remove support for pre-authentication compression. OpenSSH has only supported post-authentication compression in the server for some years. Compression before authentication significantly increases the attack surface of SSH servers and risks creating oracles that reveal information about information sent during authentication. * ssh(1), sshd(8): processing of the arguments to the "Match" configuration directive now follows more shell-like rules for quoted strings, including allowing nested quotes and \-escaped characters. If configurations contained workarounds for the previous simplistic quote handling then they may need to be adjusted. If this is the case, it's most likely to be in the arguments to a "Match exec" confition. In this case, moving the command to be evaluated from the Match line to an external shell script is easiest way to preserve compatibility with both the old and new versions. Changes since OpenSSH 9.8 ========================= This release contains a number of new features and bugfixes. New features ------------ * ssh(1), sshd(8): add support for a new hybrid post-quantum key exchange based on the FIPS 203 Module-Lattice Key Enapsulation mechanism (ML-KEM) combined with X25519 ECDH as described by https://datatracker.ietf.org/doc/html/draft-kampanakis-curdle-ssh-pq-ke-03 This algorithm "mlkem768x25519-sha256" is available by default. * ssh(1): the ssh_config "Include" directive can now expand environment as well as the same set of %-tokens "Match Exec" supports. * sshd(8): add a sshd_config "RefuseConnection" option that, if set will terminate the connection at the first authentication request. * sshd(8): add a "refuseconnection" penalty class to sshd_config PerSourcePenalties that is applied when a connection is dropped by the new RefuseConnection keyword. * sshd(8): add a "Match invalid-user" predicate to sshd_config Match options that matches when the target username is not valid on the server. * ssh(1), sshd(8): update the Streamlined NTRUPrime code to a substantially faster implementation. * ssh(1), sshd(8): the hybrid Streamlined NTRUPrime/X25519 key exchange algorithm now has an IANA-assigned name in addition to the "@openssh.com" vendor extension name. This algorithm is now also available under this name "sntrup761x25519-sha512" * ssh(1), sshd(8), ssh-agent(1): prevent private keys from being included in core dump files for most of their lifespans. This is in addition to pre-existing controls in ssh-agent(1) and sshd(8) that prevented coredumps. This feature is supported on OpenBSD, Linux and FreeBSD. * All: convert key handling to use the libcrypto EVP_PKEY API, with the exception of DSA. * sshd(8): add a random amount of jitter (up to 4 seconds) to the grace login time to make its expiry unpredictable. Bugfixes -------- * sshd(8): relax absolute path requirement back to what it was prior to OpenSSH 9.8, which incorrectly required that sshd was started with an absolute path in inetd mode. bz3717 * sshd(8): fix regression introduced in openssh-9.8 that swapped the order of source and destination addresses in some sshd log messages. * sshd(8): do not apply authorized_keys options when signature verification fails. Prevents more restrictive key options being incorrectly applied to subsequent keys in authorized_keys. bz3733 * ssh-keygen(1): include pathname in some of ssh-keygen's passphrase prompts. Helps the user know what's going on when ssh-keygen is invoked via other tools. Requested in GHPR503 * ssh(1), ssh-add(1): make parsing user@host consistently look for the last '@' in the string rather than the first. This makes it possible to more consistently use usernames that contain '@' characters. * ssh(1), sshd(8): be more strict in parsing key type names. Only allow short names (e.g "rsa") in user-interface code and require full SSH protocol names (e.g. "ssh-rsa") everywhere else. bz3725 * regress: many performance and correctness improvements to the re-keying regression test. * ssh-keygen(1): clarify that ed25519 is the default key type generated and clarify that rsa-sha2-512 is the default signature scheme when RSA is in use. GHPR505 * sshd(8): fix minor memory leak in Subsystem option parsing; GHPR515 * All: additional hardening and consistency checks for the sshbuf code. * sshd(8): reduce default logingrace penalty to ensure that a single forgotton login that times out will be below the penalty threshold. * ssh(1): fix proxy multiplexing (-O proxy) bug. If a mux started with ControlPersist then later has a forwarding added using mux proxy connection and the forwarding was used, then when the mux proxy session terminated, the mux master process would issue a bad message that terminated the connection. Portability ----------- * sync contrib/ssh-copy-id to the latest upstream version. * regress: improve portablility for some awk(1) usage (e.g. Solaris) * In the contrib/redhat RPM spec file, without_openssl was previously incorrectly enabled unconditionally. * sshd(8) restore audit call before exit that regressed in openssh-9.8 Fixes an issue where the SSH_CONNECTION_ABANDON event was not recorded. * sshd(8): add support for class-imposed loging restrictions on FreeBSD. Allowing auth_hostok(3) and auth_timeok(3) to control logins. * Build fixes for Musl libc. * Fix detection of setres*id on GNU/Hurd Checksums: ========== - SHA1 (openssh-9.9.tar.gz) = 080acf6ff0b862e8faa3baa3920a079536d28e85 - SHA256 (openssh-9.9.tar.gz) = h1xwa7CVcJfN7I9MgxxPBpUELzo+tnmLy+6slYHTUtw= - SHA1 (openssh-9.9p1.tar.gz) = 5ded7eb0add0b02b5d1a1c4bf5cb2c89d2117b53 - SHA256 (openssh-9.9p1.tar.gz) = s0P7zb/4fxWxmG5uFdbU/Jp9NgZr5rf7UHCHuo+WbAI= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
OpenSSH 9.8 was released on 2024-07-01. It is available from the mirrors listed at https://www.openssh.com/. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Security ======== This release contains fixes for two security problems, one critical and one minor. 1) Race condition in sshd(8) A critical vulnerability in sshd(8) was present in Portable OpenSSH versions between 8.5p1 and 9.7p1 (inclusive) that may allow arbitrary code execution with root privileges. Successful exploitation has been demonstrated on 32-bit Linux/glibc systems with ASLR. Under lab conditions, the attack requires on average 6-8 hours of continuous connections up to the maximum the server will accept. Exploitation on 64-bit systems is believed to be possible but has not been demonstrated at this time. It's likely that these attacks will be improved upon. Exploitation on non-glibc systems is conceivable but has not been examined. Systems that lack ASLR or users of downstream Linux distributions that have modified OpenSSH to disable per-connection ASLR re-randomisation (yes - this is a thing, no - we don't understand why) may potentially have an easier path to exploitation. OpenBSD is not vulnerable. We thank the Qualys Security Advisory Team for discovering, reporting and demonstrating exploitability of this problem, and for providing detailed feedback on additional mitigation measures. 2) Logic error in ssh(1) ObscureKeystrokeTiming In OpenSSH version 9.5 through 9.7 (inclusive), when connected to an OpenSSH server version 9.5 or later, a logic error in the ssh(1) ObscureKeystrokeTiming feature (on by default) rendered this feature ineffective - a passive observer could still detect which network packets contained real keystrokes when the countermeasure was active because both fake and real keystroke packets were being sent unconditionally. This bug was found by Philippos Giavridis and also independently by Jacky Wei En Kung, Daniel Hugenroth and Alastair Beresford of the University of Cambridge Computer Lab. Worse, the unconditional sending of both fake and real keystroke packets broke another long-standing timing attack mitigation. Since OpenSSH 2.9.9 sshd(8) has sent fake keystoke echo packets for traffic received on TTYs in echo-off mode, such as when entering a password into su(8) or sudo(8). This bug rendered these fake keystroke echoes ineffective and could allow a passive observer of a SSH session to once again detect when echo was off and obtain fairly limited timing information about keystrokes in this situation (20ms granularity by default). This additional implication of the bug was identified by Jacky Wei En Kung, Daniel Hugenroth and Alastair Beresford and we thank them for their detailed analysis. This bug does not affect connections when ObscureKeystrokeTiming was disabled or sessions where no TTY was requested. Future deprecation notice ========================= OpenSSH plans to remove support for the DSA signature algorithm in early 2025. This release disables DSA by default at compile time. DSA, as specified in the SSHv2 protocol, is inherently weak - being limited to a 160 bit private key and use of the SHA1 digest. Its estimated security level is only 80 bits symmetric equivalent. OpenSSH has disabled DSA keys by default since 2015 but has retained run-time optional support for them. DSA was the only mandatory-to- implement algorithm in the SSHv2 RFCs, mostly because alternative algorithms were encumbered by patents when the SSHv2 protocol was specified. This has not been the case for decades at this point and better algorithms are well supported by all actively-maintained SSH implementations. We do not consider the costs of maintaining DSA in OpenSSH to be justified and hope that removing it from OpenSSH can accelerate its wider deprecation in supporting cryptography libraries. This release, and its deactivation of DSA by default at compile-time, marks the second step in our timeline to finally deprecate DSA. The final step of removing DSA support entirely is planned for the first OpenSSH release of 2025. DSA support may be re-enabled in OpenBSD by setting "DSAKEY=yes" in Makefile.inc. To enable DSA support in portable OpenSSH, pass the "--enable-dsa-keys" option to configure. Potentially-incompatible changes -------------------------------- * all: as mentioned above, the DSA signature algorithm is now disabled at compile time. * sshd(8): the server will now block client addresses that repeatedly fail authentication, repeatedly connect without ever completing authentication or that crash the server. See the discussion of PerSourcePenalties below for more information. Operators of servers that accept connections from many users, or servers that accept connections from addresses behind NAT or proxies may need to consider these settings. * sshd(8): the server has been split into a listener binary, sshd(8), and a per-session binary "sshd-session". This allows for a much smaller listener binary, as it no longer needs to support the SSH protocol. As part of this work, support for disabling privilege separation (which previously required code changes to disable) and disabling re-execution of sshd(8) has been removed. Further separation of sshd-session into additional, minimal binaries is planned for the future. * sshd(8): several log messages have changed. In particular, some log messages will be tagged with as originating from a process named "sshd-session" rather than "sshd". * ssh-keyscan(1): this tool previously emitted comment lines containing the hostname and SSH protocol banner to standard error. This release now emits them to standard output, but adds a new "-q" flag to silence them altogether. * sshd(8): (portable OpenSSH only) sshd will no longer use argv[0] as the PAM service name. A new "PAMServiceName" sshd_config(5) directive allows selecting the service name at runtime. This defaults to "sshd". bz2101 * (portable OpenSSH only) Automatically-generated files, such as configure, config.h.in, etc will now be checked in to the portable OpenSSH git release branch (e.g. V_9_8). This should ensure that the contents of the signed release branch exactly match the contents of the signed release tarball. Changes since OpenSSH 9.7 ========================= This release contains mostly bugfixes. New features ------------ * sshd(8): as described above, sshd(8) will now penalise client addresses that, for various reasons, do not successfully complete authentication. This feature is controlled by a new sshd_config(5) PerSourcePenalties option and is on by default. sshd(8) will now identify situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit bugs in sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum configurable threshold, then all connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range) until the penalty expire. Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. Address ranges may be fully exempted from penalties, e.g. to guarantee access from a set of trusted management addresses, using the new sshd_config(5) PerSourcePenaltyExemptList option. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. This option is enabled by default. * ssh(8): allow the HostkeyAlgorithms directive to disable the implicit fallback from certificate host key to plain host keys. Bugfixes -------- * misc: fix a number of inaccuracies in the PROTOCOL.* documentation files. GHPR430 GHPR487 * all: switch to strtonum(3) for more robust integer parsing in most places. * ssh(1), sshd(8): correctly restore sigprocmask around ppoll() * ssh-keysign(8): stricter validation of messaging socket fd GHPR492 * sftp(1): flush stdout after writing "sftp>" prompt when not using editline. GHPR480 * sftp-server(8): fix home-directory extension implementation, it previously always returned the current user's home directory contrary to the spec. GHPR477 * ssh-keyscan(1): do not close stdin to prevent error messages when stdin is read multiple times. E.g. echo localhost | ssh-keyscan -f - -f - * regression tests: fix rekey test that was testing the same KEX algorithm repeatedly instead of testing all of them. bz3692 * ssh_config(5), sshd_config(5): clarify the KEXAlgorithms directive documentation, especially around what is supported vs available. bz3701. Portability ----------- * sshd(8): expose SSH_AUTH_INFO_0 always to PAM auth modules unconditionally. The previous behaviour was to expose it only when particular authentication methods were in use. * build: fix OpenSSL ED25519 support detection. An incorrect function signature in configure.ac previously prevented enabling the recently added support for ED25519 private keys in PEM PKCS8 format. * ssh(1), ssh-agent(8): allow the presence of the WAYLAND_DISPLAY environment variable to enable SSH_ASKPASS, similarly to the X11 DISPLAY environment variable. GHPR479 * build: improve detection of the -fzero-call-used-regs compiler flag. bz3673. * build: relax OpenSSL version check to accept all OpenSSL 3.x versions. * sshd(8): add support for notifying systemd on server listen and reload, using a standalone implementation that doesn't depend on libsystemd. bz2641 Checksums: ========== - SHA1 (openssh-9.8.tar.gz) = bc45cedae7f70b41e9922ef4c9f56e74b9a659b7 - SHA256 (openssh-9.8.tar.gz) = Dnc69VLWFBFdiaz8wySPlvHjb7wZfh/kblQ8ISuQr1Y= - SHA1 (openssh-9.8p1.tar.gz) = a0bb501b11349f5c5c33a269351be091dc2c2727 - SHA256 (openssh-9.8p1.tar.gz) = 3YvQAqN5tdSZ37BQ3R+pr4Ap6ARh9LtsUjxJlz9aOfM= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to [email protected]
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