Microsoft ships an out-of-band update after its September patch destabilized Remote Desktop Services and broke Plan9 host shares for WSL

Sources: primary, discussion
Summary: Microsoft's Windows release health page lists three regressions from the 2026-09-08 security update KB5124008, and out-of-band cumulative update KB5129195, released 2026-09-14, marks Remote Desktop Services instability and the Plan9 host folder share failure as resolved. Microsoft names WSL and Claude Cowork as affected by the Plan9 break, and states that administrators who applied the Group Policy mitigation for that issue must re-enable the policy before installing the update. The USB Audio Class 1.0 entry is still marked Mitigated, and Microsoft states the fix addresses the 8-channel and 3D audio symptoms only.
Why it matters: The Remote Desktop Services fix spans Windows Server 2012 through 2025 and the USB audio regression is only partly resolved, so KB5129195 is scheduled work rather than an optional catch-up.
Follow-up: Track whether Microsoft moves the USB Audio Class 1.0 entry from Mitigated to Resolved.