Microsoft releases emergency Windows 11 update to fix security patch errors

Microsoft Windows KB5129195 out-of-band update security patch Remote Desktop Services

Microsoft has released an emergency out-of-band update, KB5129195, to address critical issues caused by the September security patch (KB5124008). The emergency patch targets Windows 10 and Windows 11 users, specifically addressing versions 24H2 and 25H2.

Key fixes included in the update involve Remote Desktop Services instability, which caused connection failures and login errors, and Hyper-V issues where shared folders using the Plan 9 protocol were inaccessible. The update also resolves multi-channel audio failures for USB Audio Class 1.0 devices. Additionally, it patches a privilege escalation vulnerability (CVE-2026-62721) in the Windows User-Mode Power Service.

However, the update does not resolve all reported problems. Issues involving AMD Radeon GPU crashes, black screens, and certain Windows Explorer failures remain under investigation. Some users have also reported boot issues (UNMOUNTABLE_BOOT_VOLUME) following the installation of the emergency patch. Furthermore, some Windows 11 users have experienced broken domain connections due to the Machine Identity Isolation feature, for which Microsoft has recommended a registry-based workaround.

Entities

AMD · Hyper-V · Marcus Ash · Microsoft · Qualys · Remote Desktop Services · Windows 10 · Windows 11

Claims

What the coverage asserts, and how many sources carry each claim.

[● 7 SOURCES] The KB5129195 update addresses Remote Desktop Services instability and login failures. www.topgadget.com.br · japan.zdnet.com · news.mynavi.jp · genk.vn · trend.dk · +2 more
[● 6 SOURCES] The patch resolves issues with Hyper-V virtual machines using the Plan 9 operating system when sharing folders with a host. japan.zdnet.com · news.mynavi.jp · www.topgadget.com.br · genk.vn · trend.dk · +1 more
[● 6 SOURCES] The update addresses audio issues affecting USB Audio Class 1.0 devices, specifically fixing multi-channel audio failures. japan.zdnet.com · news.mynavi.jp · cybernoz.com · www.topgadget.com.br · www.bild.de · +1 more
[● 3 SOURCES] The emergency update does not resolve reported issues involving AMD Radeon GPU crashes or blackouts. www.topgadget.com.br · news.mynavi.jp · trend.dk
[● 3 SOURCES] The update fixes a privilege escalation vulnerability in the Windows User-Mode Power Service (CVE-2026-62721). japan.zdnet.com · news.mynavi.jp · trend.dk
[● 7 SOURCES] Microsoft released an emergency out-of-band update for Windows 11 to address issues caused by the September security patch. www.topgadget.com.br · japan.zdnet.com · news.mynavi.jp · www.bild.de · trend.dk · +2 more
[● 3 SOURCES] The update does not address reports of Windows Explorer failing to start or crashing immediately after sign-in. www.topgadget.com.br · news.mynavi.jp · trend.dk