Microsoft has shipped emergency out-of-band updates to undo the damage caused by this month’s Patch Tuesday release. The September 8 security update broke Remote Desktop Services on many Windows 11 PCs and servers. The fixes arrived on September 14, six days later.
The September 8 cumulative update, tracked as KB5124008 for the 24H2 and 25H2 branches, patched two actively exploited zero-day vulnerabilities. But it also destabilized Remote Desktop Services on affected machines, causing RDP connection failures, sign-in errors, and unresponsive servers. Related tools like Microsoft Management Console, the RDS Licensing Diagnoser, File Explorer, and even the Windows Update page sometimes stopped responding too. The same update broke Hyper-V folder sharing with Linux virtual machines. It also caused some USB Audio Class 1.0 devices to fail with a Device Manager “Code 10” error.
What the new updates fix
Microsoft’s support page for KB5129195 confirms the fix directly. The page states that in affected environments, “RDS might become unstable, causing RDP connection and sign-in failures or servers to become unresponsive during Remote Desktop configuration.” That same update also resolves the Hyper-V folder-sharing bug affecting Linux virtual machines.
On audio, the fix is only partial. Microsoft says it resolved failures specific to 8-channel and 3D audio modes on USB Audio Class 1.0 devices. Other audio symptoms from the same devices, including the Code 10 error and complete audio loss, remain unresolved. Microsoft says it is still investigating a fix for those.
Which update applies to your PC
Microsoft split the fix across four separate KBs depending on which Windows 11 branch you run.
- 24H2 and 25H2: KB5129195, bringing builds to 26200.9457 and 26100.9457
- 23H2 and 22H2: KB5129242, bringing the build to 22631.7584
- 26H1 (Insider/preview channel): KB5129194, bringing the build to 28000.2956
- Hotpatch-enrolled Enterprise/Windows 365 devices on 24H2/25H2: KB5129241, a restart-free hotpatch on builds 26200.9448 and 26100.9448
All four also carry protection for CVE-2026-62721, a Windows User-Mode Power Service elevation-of-privilege flaw disclosed alongside the fixes.
Do you need to do anything?
No manual action is required. Microsoft’s documentation confirms the update downloads and installs automatically through Windows Update and Microsoft Update once your device already has the September 8 security update. It does not require a restart on hotpatch-enrolled systems. If you want to check manually, go to Settings > Windows Update and select Check for updates. Admins managing fleets through WSUS or Windows Update for Business can also pull the standalone packages from the Microsoft Update Catalog.
A security patch that knocks out Remote Desktop Services for six days is a real cost. Anyone who relies on RDP for remote work or server administration felt it. The USB audio bug still isn’t fully resolved either. If you depend on multichannel USB audio devices, Microsoft’s interim advice remains to switch to a 2-channel configuration until a complete fix ships.
For the original list of known issues from this update, see our earlier coverage of KB5124008’s known issues and workarounds.
Source: Microsoft Support
