Microsoft Issues Emergency Patch for RDS and Hyper-V Disruptions

Microsoft has released an emergency out-of-band (OOB) update to resolve significant stability issues affecting Remote Desktop Services (RDS) and Hyper-V. The update, identified as KB5129195, fixes disruptions caused by the company’s September 8 security update, which addressed a record 974 Common Vulnerabilities and Exposures (CVEs).

Microsoft acknowledged that the initial Patch Tuesday deployment caused several issues in various environments. In some cases, RDS became unstable, leading to failed Remote Desktop Protocol (RDP) connections, sign-in difficulties, or servers becoming stuck on the “Please wait for the Remote Desktop Configuration” screen.

The instability also impacted secondary tools. Users reported that the Microsoft Management Console (MMC), RDS Licensing Diagnoser, and File Explorer became unresponsive. The Windows Update interface also may have failed to respond, displaying a continuous loading indicator.

Resolving Hyper-V and Hardware Issues

The emergency patch also addresses technical problems for users of Hyper-V, Claude Cowork, and the Windows Subsystem for Linux (WSL). Specifically, Microsoft noted that while affected virtual machines start normally, folders shared from a Windows host using the Plan9 protocol may not appear or remain inaccessible within the guest environment.

The update resolves an issue where USB Audio Class 1.0 devices failed to start or produced no audio following the original September 8 update.

Microsoft stated that IT administrators who previously implemented temporary mitigations through Group Policy do not need to take additional action before installing the KB5129195 update. As the patch is cumulative, it includes all previous security improvements and issue resolutions.

This release marks the sixth emergency patch Microsoft has issued to correct failures stemming from the September Patch Tuesday cycle.