GoKawiil21,899 Exchange servers still unpatched against CVE-2026-62911 flaw
Shadowserver has identified nearly 22,000 internet-exposed Microsoft Exchange servers that remain unpatched against CVE-2026-62911, a high-severity authentication bypass flaw affecting Exchange Server 2016, 2019, and Subscription Edition. Most vulnerable systems are located in the United States and Germany, where officials say roughly 85% of on-premises Exchange servers remain exposed despite Microsoft releasing a fix in August 2026.
GoKawiil's interpretation of the reporting above, not reported fact.
Exploit code for the flaw is already circulating online according to the Dutch NCSC, meaning attackers can quickly weaponize it to seize entire mailbox environments, read and send emails, and pull attachments from every user on a compromised server. With so many servers unpatched months after the fix, this creates a sizable attack surface for espionage and business email compromise campaigns, especially since older Exchange versions now depend on paid Extended Security Updates.
- Nearly 22,000 exposed Exchange servers remain unpatched against CVE-2026-62911.
- Public exploit code already exists, raising the urgency for organizations to patch.
- Germany reports about 85% of its on-premises Exchange servers are still vulnerable.
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Published there as: “Nearly 22,000 Microsoft Exchange servers vulnerable to hijack attacks”
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