What broke and why the fix matters
Microsoft dropped emergency out-of-band patches on September 14, 2026 to rescue Remote Desktop sessions that went dark after the September security rollup.
The September updates unintentionally broke Remote Desktop Services (RDS) on a wide range of Windows client and server editions. For enterprises that rely on RDS for day‑to‑day access, the outage meant lost productivity and, in some cases, inability to manage servers remotely.
Technical details
The regression traces back to two September patches: KB5122871 for Windows Server 2025 and KB5122882 for Windows Server 2022. Both introduced a change in the RDS stack that prevented new connections from being established.
Microsoft had already published Group Policy work‑arounds, but those require manual configuration and do not cover every scenario.
Uninstalling the September patches restores RDS, but it also rolls back the security fixes they delivered—a trade‑off most organizations cannot afford.
What the emergency updates fix
- Windows 10 21H2 & 22H2 (KB5129236)
- Windows 11 24H2 & 25H2 (KB5129195)
- Windows 11 26H1 (KB5129194)
- Windows Server 2019 (KB5129238)
- Windows Server 2022 (KB5129237)
- Windows Server 2025 (KB5129235)
In addition to RDS, the patches also resolve a Hyper‑V bug that broke applications using the Host Compute Service‑managed virtual machines, and an audio glitch that left some USB Audio Class 1.0 devices silent in multichannel mode.
Who needs to act
The fix applies to any machine running the listed client or server builds. Organizations that have deployed the September security rollup but still need RDS must prioritize the out‑of‑band updates.
Defensive steps
- Verify the September KB numbers (KB5122871, KB5122882) are installed.
- Download and install the appropriate out‑of‑band KB for your OS:
- Via Windows Update, Windows Update for Business, Microsoft Update Catalog, or WSUS for client builds.
- Via Microsoft Update Catalog for Server 2019/2022/2025.
- Test RDS connectivity after the patch; confirm remote sessions open without error.
- If you cannot apply the out‑of‑band update immediately, enable the published Group Policy mitigations as a temporary bridge.
- Retain the September security patches after the out‑of‑band fix is in place; do not uninstall them unless you have an alternate security compensating control.
Bottom line
Skipping the emergency patches will keep RDS broken and force admins into risky work‑arounds. Applying the out‑of‑band updates restores remote management while preserving the September security posture.