Windows 11 25H2 and 24H2 Out-of-Band Update

 

Microsoft released Out-of-Band (OOB) update KB5129195 (OS 26200.9457 and 26100.9457) for Windows 11 versions 25H2 and 24H2 on September 14, 2026. The update includes updates from previous releases, along with additional security and non-security improvements. 

Improvements

This OOB update includes the following improvements:

• [Security] This update includes protections documented in CVE-2026-62721, which refers to a Windows User-Mode Power Service (UMPS) Elevation of Privilege vulnerability.
• [Remote Desktop Services (known issue)] Fixed: This update addresses an issue affecting Remote Desktop Services (RDS) after installing the September 2026 Windows security update (KB5122880). In affected environments, RDS might become unstable, causing RDP connection and sign-in failures or servers to become unresponsive during Remote Desktop configuration. Related tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, File Explorer, and the Windows Update page, might also stop responding.
• [Hyper-V (known issue)] Fixed: Some applications that use HCS-managed virtual machines experienced issues when sharing host folder with Linux VMs using Plan9. Folders shared from the Windows host using Plan9 did not appear or could not be accessed in the guest environment.
• [8-channel or 3D audio modes] Fixed: Some USB Audio Class 1.0 devices functioning as expected in standard stereo configurations failed when using multichannel audio features, including 8-channel or 3D audio modes. (Note: There are other audio symptoms not resolved in this OOB update. See the “Known issues in this update” section for more information.)

Component updates
Windows 11 servicing stack update (KB5124007) - 22621.9441
This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.

Known issues in this update

USB Audio Class 1.0 devices with error Code 10 or no output

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

Resolution
Microsoft is working on a resolution and will update this documentation when more information is available.

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