Emergency Windows patches target RDS failures

Administrators who patched their Windows and Windows Server systems in September 2026 found some of those machines in worse shape than before. Remote Desktop Services stopped behaving, and Microsoft has now pushed out-of-band updates to correct it.

The company released multiple emergency packages on September 14, aimed at systems where this month's security updates left Remote Desktop unstable.

What the September updates broke

According to Microsoft, the September 2026 security updates caused Remote Desktop Services (RDS) to become unstable on affected systems. The consequences included RDP connection and sign-in failures and, in some cases, unresponsive servers.

The trouble did not stop at the RDP listener. Affected systems could also run into problems with related components and tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, File Explorer, and the Windows Update page, any of which could stop responding.

Microsoft had previously acknowledged the issue after Windows administrators reported widespread RDS problems following the September updates.

The out-of-band packages Microsoft shipped

Microsoft says the September Server updates address RDS failures introduced by September's KB5122871 update on Windows Server 2025 and KB5122882 on Windows Server 2022.

Five updates make up the emergency release, split across Windows client and server products:

• Windows 11 26H1: KB5129194
• Windows 11 24H2 and 25H2: KB5129195
• Windows 10 21H2 and 22H2: KB5129236
• Windows Server 2025: KB5129235
• Windows Server 2022: KB5129237

Where each fix comes from

The Windows 11 26H1 update, KB5129194, is available through Windows Update, Windows Update for Business, the Microsoft Update Catalog, and Windows Server Update Services (WSUS).

For Windows Server 2022 and Windows Server 2025, the out-of-band updates are available through the Microsoft Update Catalog.

Microsoft also released KB5129195 for Windows 11 24H2 and 25H2 and KB5129236 for Windows 10 21H2 and 22H2 to address the RDS failures affecting those systems.

The Windows Server packages are the ones Microsoft ties directly to the RDS failures, while the client updates cover the same class of symptom on Windows 10 and Windows 11 builds.

Group Policy came first, then the code

Before shipping the out-of-band packages, Microsoft had provided Group Policy mitigations for affected Windows and Windows Server systems while it worked on a permanent fix.

Administrators also reported that uninstalling the September security updates restored Remote Desktop functionality, but it also removed the security fixes included with those updates — a trade-off Microsoft's emergency packages are meant to resolve without forcing that choice.

Hyper-V shared folders also on the list

The out-of-band Windows 11 updates also resolve a Hyper-V issue affecting applications that use Host Compute Service (HCS)-managed virtual machines.

Microsoft says some applications experienced problems when sharing Windows host folders with Linux virtual machines using Plan9, causing shared folders to either not appear inside the guest environment or become inaccessible.

An audio fix, and what it leaves out

The updates also fix an audio issue affecting some USB Audio Class 1.0 devices when used with multichannel audio, including 8-channel and 3D audio modes.

Microsoft says affected devices continued to work as expected in standard stereo mode but could fail when switching to these multichannel configurations.

The emergency updates do not resolve all of the USB audio problems introduced by the September updates. Microsoft's release notes describe the remaining symptoms in detail:

"After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio."

Microsoft goes on to enumerate what affected users may see, again in its own words:

"Affected devices might experience one or more of the following symptoms: The device displays an error in Device Manager: \"This device cannot start (Code 10).\" No audio output. Volume controls are unresponsive or remain at zero. Sound settings are unresponsive or unavailable. This issue is limited to USB Audio Class 1.0 devices."

— Microsoft, in the release notes for the September 2026 updates

The company says it is working on a fix for the remaining audio problems.

What administrators are working with

The scope of the emergency release covers five separate updates and two distinct server platforms, plus three client build families. The failure modes administrators reported range from RDP connection and sign-in failures to unresponsive servers, with collateral problems in MMC, RDS Licensing Diagnoser, File Explorer, and the Windows Update page.

Microsoft's stated fix path splits by product. Windows Server 2022 and Windows Server 2025 customers pull their packages from the Microsoft Update Catalog. Windows 11 26H1 customers can get KB5129194 through Windows Update, Windows Update for Business, the Microsoft Update Catalog, and WSUS. Windows 11 24H2 and 25H2 receive KB5129195, and Windows 10 21H2 and 22H2 receive KB5129236.

The Hyper-V and USB audio fixes are documented as part of the out-of-band Windows 11 updates. The remaining USB Audio Class 1.0 symptoms are still outstanding, and Microsoft has said only that a fix is in progress.

Reporting based on original coverage from BleepingComputer.