Microsoft has fixed a known issue caused by the August 2025 security updates, which triggers unexpected User Account Control (UAC) prompts and app installation problems for non-admin users on all Windows versions.
This issue is caused by a security patch that mitigates a Windows Installer privilege escalation vulnerability (CVE-2025-50173), which can enable authenticated attackers to gain SYSTEM privileges.
To address the CVE-2025-50173 security flaw, Microsoft has implemented new User Account Control (UAC) prompts requesting admin credentials in various situations to prevent attackers from escalating permissions.
However, these UAC prompts would also be displayed inadvertently in other scenarios, including when trying to install apps that use Windows Installer (MSI), when enabling Secure Desktop, and running MSI repair commands.
As explained when Microsoft acknowledged this bug last week, the complete list of affected platforms is extensive, and it includes both client and server platforms:
Client : Windows 11, version 24H2; Windows 11, version 23H2; Windows 11, version 22H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10, version 1809; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016; Windows 10, version 1607; Windows 10 Enterprise 2015 LTSB
: Windows 11, version 24H2; Windows 11, version 23H2; Windows 11, version 22H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10, version 1809; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016; Windows 10, version 1607; Windows 10 Enterprise 2015 LTSB Server: Windows Server 2025; Windows Server 2022; Windows Server, version 1809; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012
"To address these issues, the September 2025 Windows security update (and later updates) reduces the scope for requiring UAC prompts for MSI repairs and enables IT admins to disable UAC prompts for specific apps by adding them to an allowlist," Microsoft said.
"After installing the September 2025 update, UAC prompts will only be required during MSI repair operations if the target MSI file contains an elevated custom action."
Because UAC prompts will still be required for applications that perform custom actions, Microsoft has provided IT administrators with a method to turn off UAC prompts for specific apps after this update by including MSI files on an allowlist.
This requires adding new SecureRepairPolicy and SecureRepairWhitelist registry keys under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer using the steps detailed in this support document.
Microsoft has also resolved another bug triggered by the August 2025 security updates, which causes severe lag and stuttering issues with NDI streaming software on Windows 10 and Windows 11 systems.