Microsoft Releases Out-of-Band Update to Fix Issues Triggered by Windows 11 September 2026 Patch

Microsoft has released an out-of-band update to address several problems caused by the Windows 11 September 2026 security updates. The issues include Hyper-V Linux folder sharing failures, Remote Desktop problems, and USB audio failures.

Microsoft releases emergency update for affected Windows devices

For most supported Windows versions, it is cumulative and includes the September 8 security update. For Windows 11 26H1, 25H2, and 24H2, the update is classified as a security update. It should download automatically through Windows Update under normal update policies.

The update also includes security fixes for CVE-2026-62721. Windows 11 26H1 additionally receives a fix for CVE-2026-85921. Interestingly, this follows a growing list of problems surrounding Microsoft’s September updates. Microsoft says host folder shares might become unavailable in Hyper-V-based Linux virtual machines after the September update.

The update can also cause Remote Desktop Services to stop responding. This can prevent new sessions from being created and interfere with local and remote sign-ins. Some USB Audio Class 1.0 devices can also fail when used in multichannel audio modes. Microsoft has included fixes for these issues in the new out-of-band update.

Here’s the list of updates released for affected versions:

• Windows 11, version 26H1: KB5129194 
• Windows 11, versions 25H2 and 24H2: KB5129195 
• Windows 11, versions 25H2 and 24H2 (hotpatch): KB5129241 
• Windows 11, version 23H2: KB5129242 
• Windows Server 2025: KB5129235 
• Windows Server 2022: KB5129237 
• Windows 10, version 22H2 and Windows 10 Enterprise LTSC 2021: KB5129236 
• Windows 10 Enterprise LTSC 2019 and Windows Server 2019: KB5129238 
• Windows 10 Enterprise LTSB 2016 and Windows Server 2016: KB5129239 
• Windows Server 2012 R2: KB5129243 
• Windows Server 2012: KB5129244 

KB5124008 already fixed several earlier Windows 11 problems

KB5124008 previously addressed several problems affecting Windows 11 users. These included Teams and New Outlook launch failures on ARM64 devices. Microsoft also resolved issues involving game crashes and freezes linked to certain RGB software. Other fixes included problems affecting mouse cursor personalization and desktop personalization.

The latest OOB update is separate from those earlier fixes. It specifically addresses problems introduced by the September 8 security update. Microsoft says Windows 11 23H2 and Windows 10 22H2 ESU users receive the OOB update as an optional non-security update. They can install it through Settings > Windows Update > Check for updates.