Microsoft's sixth emergency patch of September 2026 fixes RDS breakage, Hyper-V, and USB audio regressions from record 974-CVE Patch Tuesday

Microsoft shipped five out-of-band updates on September 14, 2026 to fix Remote Desktop Services failures caused by September Patch Tuesday security updates (a record 974 CVEs) — its sixth emergency patch since the September 8 Patch Tuesday.

Microsoft confirmed that its September 2026 Patch Tuesday security updates — which fixed a record 974 CVEs — caused Remote Desktop Services failures on Windows Server 2012 and later, as well as Windows 10 and Windows 11. Symptoms included unstable RDS, RDP connections failing after several minutes, sign-in issues, servers hanging at 'Please wait for the Remote Desktop Configuration,' and unresponsive MMC, RDS Licensing Diagnoser, File Explorer, and Windows Update pages. The failures were traced to September patches KB5122871 (Windows Server 2025) and KB5122882 (Windows Server 2022). Microsoft initially published per-version Group Policy mitigations (covering KB5124008, KB5122880, KB5122878, KB5122871, KB5122882, KB5122876, KB5123099, KB5123065, KB5123066) and suggested restarting affected VMs; rolling back the updates restored RDS but removed the month's security fixes. On September 14, 2026, Microsoft released five emergency out-of-band updates — its sixth emergency patch since the September 8 Patch Tuesday: KB5129194 (Windows 11 26H1), KB5129195 (Windows 11 24H2/25H2), KB5129236 (Windows 10), KB5129235 (Windows Server 2025), and KB5129237 (Windows Server 2022), covering Windows 10, Windows 11, and Windows Server 2019–2025. The Windows 11 updates also fix a Hyper-V Plan9 shared-folder issue affecting WSL and Claude Cowork, plus some USB Audio Class 1.0 multichannel problems. Sources disagree on USB audio completeness: BleepingComputer reports some USB Audio Class 1.0 device failures remain unresolved, while Infosecurity Magazine describes the USB audio failures as resolved.

• September 2026 Patch Tuesday (September 8) fixed a record 974 CVEs, per Infosecurity Magazine.
• RDS failures affected Windows Server 2012 and later plus Windows 10 and Windows 11; symptoms included RDP connections failing after several minutes, sign-in issues, servers hanging at 'Please wait for the Remote Desktop Configuration,' and…
• Failures were traced to September patches KB5122871 (Windows Server 2025) and KB5122882 (Windows Server 2022).
• Microsoft's Group Policy mitigations covered KB5124008, KB5122880, KB5122878, KB5122871, KB5122882, KB5122876, KB5123099, KB5123065, and KB5123066; VM restarts and update rollback were workarounds, but rollback removed the month's security…
• Emergency out-of-band updates released September 14, 2026: KB5129194 (Windows 11 26H1), KB5129195 (Windows 11 24H2/25H2), KB5129236 (Windows 10), KB5129235 (Windows Server 2025), and KB5129237 (Windows Server 2022).
• The out-of-band release is Microsoft's sixth emergency patch since the September 8, 2026 Patch Tuesday.
• Windows 11 out-of-band updates also fix a Hyper-V Plan9 shared-folder issue affecting WSL and Claude Cowork, plus some USB Audio Class 1.0 multichannel problems; BleepingComputer says some USB audio device failures remain unresolved, while…