The Update BureauKB5129195: Cumulative update for Windows 11, versions 24H2, 25H2 and 26H2, September 2026. Remote Desktop failures and USB multichannel audio fixed
Protects against a Windows User-Mode Power Service elevation-of-privilege flaw and addresses Remote Desktop instability and USB multichannel audio failures. Other USB Audio Class 1.0 problems remain.
Does it affect you? Applies to: Devices running Windows 11 versions 24H2, 25H2, or 26H2.
What changes
Fixes 3 changes
Remote Desktop Services
-
Remote Desktop connections and sign-ins work more reliably in affected environments; servers and related tools are less likely to become unresponsive during Remote Desktop configuration.1
Addresses instability after installing the September 2026 Windows security update, including issues with RDP, MMC, RDS Licensing Diagnoser, File Explorer, and the Windows Update page.
Hyper-V
For: applications using HCS-managed virtual machines with Linux guests
-
Folders shared from Windows hosts can appear and be accessed in Linux virtual machines.2
Fixes Plan9 folder sharing for Linux VMs managed by HCS.
8-channel or 3D audio modes
For: devices using USB Audio Class 1.0 audio
-
Some USB Audio Class 1.0 devices can use multichannel audio modes, including 8-channel and 3D audio, again.3
This resolves the multichannel-audio symptom only; other USB Audio Class 1.0 symptoms remain unresolved.
Improvements 2 changes
Security
-
Adds protection against a vulnerability that could let an attacker gain elevated privileges.4
The protection covers CVE-2026-62721, a Windows User-Mode Power Service (UMPS) Elevation of Privilege vulnerability.
Windows servicing stack
-
The component that installs Windows updates receives quality improvements to help devices reliably receive and install updates.5
Includes servicing stack update KB5124007, build 22621.9441.
Known issues
-
USB audio devices might fail to start or produce no sound
Some USB Audio Class 1.0 devices might show Code 10, produce no audio, or have unresponsive volume controls or sound settings. This update resolves the issue only for 8-channel or 3D audio modes; other symptoms remain unresolved.6
How to apply the workaround WorkaroundIT administrators who need an immediate workaround for symptoms not addressed by this update can contact Microsoft Support for Business.6
-
Devices might experience a black screen or desktop loading issues after sign-in
Some devices might show a black screen or have desktop loading problems after sign-in. This issue is resolved by updates released on or after October 13, 2026, such as KB5127648.7
Resolution Fixed in KB5127648Install KB5127648 (or a later cumulative update) on affected devices. No manual workaround is required after updating.
-
File History might stop working after installing September 2026 Windows update
Some File History users might be unable to create or update backups, and might see a misleading request to reconnect a working drive. KB5124010 or a later update resolves this issue.8
Resolution Fixed in KB5124010Install KB5124010 (or a later cumulative update) on affected devices. No manual workaround is required after updating.
-
Domain-joined devices might lose their secure trust relationship with the domain
Some domain-joined devices using Credential Guard protected machine accounts might lose their secure connection to an on-premises Active Directory domain and fail to accept interactive domain sign-ins. KB5124010 resolves this issue.9
Resolution Fixed in KB5124010Install KB5124010 (or a later cumulative update) on affected devices. No manual workaround is required after updating.
Technical details
Data sheet · Security · Downloads · Components Click to collapse or expand
Data sheet
- Released
- 2026-09-14
- Classification
- Security Updates
- Type
- Cumulative update
- Restart
- Required
- Replaces
-
KB5124008, KB5120998, KB5121003, KB5101684
+60 earlier
KB5121767, KB5101650, KB5095093, KB5094126, KB5089573, KB5089549, KB5083631, KB5083769, KB5086672, KB5079391, KB5085516, KB5079473, KB5077241, KB5077181, KB5074105, KB5078127, KB5077744, KB5074109, KB5072033, KB5070311, KB5068861, KB5067036, KB5070773, KB5066835, KB5065789, KB5068221, KB5065426, KB5064081, KB5063878, KB5062660, KB5064489, KB5062553, KB5060829, KB5063060, KB5060842, KB5058499, KB5061977, KB5058411, KB5055627, KB5059087, KB5055523, KB5053656, KB5053598, KB5052093, KB5051987, KB5050094, KB5050009, KB5048667, KB5046740, KB5046617, KB5044384, KB5044284, KB5043178, KB5043080, KB5041865, KB5041571, KB5040529, KB5040435, KB5039304, KB5039239 - Replaced by
- KB5127648
| Version | Build | Channel |
|---|---|---|
| 24H2 | 26100.9457 | General availability |
| 25H2 | 26200.9457 | General availability |
| 26H2 | 26300.9457 | General availability |
| 26H2 | 26300.9457 | Release Preview Channel |
Security
| Vulnerability | Severity | CVSS |
|---|---|---|
|
Windows User-Mode Power Service (UMPS) Elevation of Privilege Vulnerability
|
Important | 7.8 |
Downloads (Microsoft Update Catalog)
Updated components
775 files changed since the previous update for the same versions.
| Top changed components | Files |
|---|---|
| Graphics and display | 9 |
| Audio | 6 |
| Hyper-V and virtualization | 4 |
| Networking | 4 |
| Secure Boot | 4 |
| Kernel | 3 |
| Printing | 3 |
| Remote Desktop | 2 |
| File Explorer and shell | 1 |
| Magnifier | 1 |
| Search | 1 |
Verified in package: changed files confirm Remote Desktop Services, 8-channel or 3D audio modes.
Page history
-
Known issue resolved: USB Audio Class 1.0 devices with error Code 10 or no output (KB5129195)
Sources
Cited passages from Microsoft's official notes (9)
-
1.
[Remote Desktop Services (known issue)] Fixed: This update addresses an issue affecting Remote Desktop Services (RDS) after installing the September 2026 Windows security update
support.microsoft.com -
2.
[Hyper-V (known issue)] Fixed: Some applications that use HCS-managed virtual machines experienced issues when sharing host folder with Linux VMs using Plan9.
support.microsoft.com -
3.
[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.
support.microsoft.com -
4.
[Security] This update includes protections documented in CVE-2026-62721, which refers to a Windows User-Mode Power Service (UMPS) Elevation of Privilege vulnerability.
support.microsoft.com -
5.
This update makes quality improvements to the servicing stack, which is the component that installs Windows updates.
support.microsoft.com -
6.
IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.
learn.microsoft.com -
7.
This issue is resolved in Windows updates released on and after October 13, 2026 such as KB5127648.
support.microsoft.com -
8.
This issue is resolved in Windows updates released on and after September 22, 2026 such as KB5124010.
support.microsoft.com -
9.
This issue was resolved by Windows updates released September 22, 2026 (KB5124010), and updates released after that date.
learn.microsoft.com
Checked automatically: 7 of 8 checks passed, 9 quoted passages · compared with Microsoft's page on Nov 13, 2026
- Quotes found in the official pages: passed
- Numbers found in the sources: passed
- Vulnerabilities from the dossier only: passed
- Links to allowed domains only: passed
- Every official change covered: passed
- Readable plain text: passed
- Changes confirmed by the file list: passed
- Sources agree: not passed
A second AI read the text against the sources: correctness 4/5, clarity 4/5, completeness 5/5. How we work
Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake