Overview
- Microsoft released the September security update KB5124008 (KB5124012 for 26H1) on Sept. 8, 2026 and users soon reported USB audio devices failing to start or producing no sound.
- Microsoft has confirmed the regression affects Windows 11 versions 24H2, 25H2 and 26H1 and says it is working on a fix and will update its documentation when ready.
- Affected hardware shows Device Manager errors such as "This device cannot start (Code 10)," may have unresponsive volume controls, and often loses multichannel features that can sometimes be restored by switching to two‑channel stereo.
- Independent outlets and user reports link the same update to other problems including Remote Desktop Service instability, WSL and Linux VM file access issues, Explorer.exe crashes, File History failures, and some AMD Radeon crashes, though Microsoft has not confirmed all these reports.
- Security researchers warn users not to rush to uninstall the patch because it addresses critical vulnerabilities, and administrators should await Microsoft's fix or use temporary workarounds such as reverting multichannel settings or switching to stereo.