As of September 14, 2026, Microsoft has released a series of out-of-band updates for Windows. For Windows 11 (versions 24H2 and 25H2), the cumulative emergency patch is available under the identifier KB5129195. The update is primarily aimed at users and administrators who have been struggling with remote maintenance and desktop session failures since the regular security Patch Tuesday on September 8, 2026.
Security update broke Remote Desktop Services
The emergency patch was triggered by last week’s security updates (including update KB5122878). Following their installation, severe errors occurred within Remote Desktop Services (RDS—a Windows service enabling remote access to other computers over a network). Affected users were abruptly disconnected from active sessions or found themselves completely unable to log in.
In addition, the connection problems led to server performance drops and crashes of administrative utilities: the Microsoft Management Console (MMC), the RDS Licensing Diagnoser tool, Windows Explorer, and the Windows Update settings page all became unresponsive at times. Because an automated mitigation previously rolled out by Microsoft (Known Issues Rollback, KIR) failed to resolve the issue across all environments, the company has now followed up with full out-of-band updates, as reported by Born’s IT and Windows Blog.
Fixes for Hyper-V and USB audio
Beyond the Remote Desktop issues, update KB5129195 addresses two additional bugs:
- Hyper-V file shares: In applications managing virtual machines via the Host Compute Service (HCS), shared Windows folders using the Plan9 protocol failed to appear or were blocked in Linux guest sessions. This access has been restored to normal working order with the update.
- Multichannel audio: Certain USB audio devices using the Audio Class 1.0 standard encountered glitches as soon as 8-channel or 3D audio modes were enabled, even though standard stereo playback functioned properly. Other known audio bugs of this type remain unresolved for now.
Availability and recommendations
In addition to Windows 11, Microsoft is rolling out corresponding fixes for older operating systems: Windows 10 (21H2 through 22H2) receives update KB5129236, while packages KB5129235 through KB5129239 are available for Windows Server 2016 through Windows Server 2025. Corresponding patches have also been issued for Windows Server 2012 and 2012 R2.
The updates are rolling out gradually via Windows Server Update Services (WSUS) and are also available for manual download from the Microsoft Update Catalog. Users and IT administrators who rely on Remote Desktop connections or are affected by the aforementioned virtualization and audio issues should deploy the update promptly. Those running Windows 11 strictly on standalone PCs without remote maintenance services can afford to wait.
Sources: Stadt-Bremerhaven, Borncity.com/blog
