Microsoft has pushed out an emergency Windows 11 patch after last week's Patch Tuesday release broke several things at once. KB5129195 is a mandatory out-of-band cumulative update for Windows 11 24H2 and 25H2, taking them to builds 26100.9457 and 26200.9457. Windows 11 26H1 gets its own companion patch, KB5129194.
The fixes cover Remote Desktop Services, which Microsoft says could turn unstable and cause connection or sign-in failures. There's also a Hyper-V fix for apps that couldn't reach host folders shared with Linux VMs over Plan9, which is what had been breaking Claude Cowork on Windows. Multichannel audio on some USB Audio Class 1.0 devices works again too, and an elevation of privilege flaw in the User-Mode Power Service gets a second patch after the first one apparently didn't fully close it.
What isn't fixed is probably the part PC gamers care about. Radeon owners have been reporting driver timeouts, black screens, vanishing displays and full system freezes since KB5124008 landed, sometimes returning right after a clean driver reinstall. Reports seem to span a wide range of cards, from the RX 6600 up to the RX 9070 XT. Microsoft still hasn't acknowledged it as a known issue, and KB5129195 lists no fix for it.
Moreover, explorer.exe crashes and File History failing to detect external drives are also still open. One audio bug stays confirmed but unpatched, where USB Audio Class 1.0 devices throw a Code 10 error or produce no sound at all. Microsoft says only that it is "working on a resolution."
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Which Windows 11 versions and build numbers does KB5129195 install on?
What changed in the Hyper-V fix for Linux VM shared folders over Plan9?
Does the emergency update do anything for Radeon black screens, driver timeouts, or system freezes?
If KB5124008 caused problems, what are the risks of rolling it back versus keeping the security fixes?
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Rolling back September's update apparently helps some users, though it also strips out security fixes from a patch covering hundreds of flaws. If you're on a Radeon card and haven't updated, sitting this one out looks like the safer call for now, especially with 26H2 already queued up for a wider rollout.
