Microsoft released an out-of-band Windows update on September 14, 2026 to repair damage caused by its September 8 Patch Tuesday security update, which broke three things. The most disruptive was Remote Desktop Services going unresponsive and blocking sign-ins, followed by broken Hyper-V host folder sharing in Linux VMs and USB Audio Class 1.0 failures in multichannel modes. The emergency patch is also a security update closing CVE-2026-62721 and, for Windows 11 26H1, CVE-2026-85921. However, it does not fully fix the USB audio problem, so a follow-up fix is still coming.

Microsoft Releases Emergency Windows Update After Patch Tuesday Breaks Remote Desktop

Microsoft had to pull the emergency trigger this week, shipping an out-of-band Windows update on September 14, 2026 to repair the damage caused by its own Patch Tuesday. The monthly security patch, released September 8, 2026, turned out to be one of those less successful ones. Three separate regressions showed up once devices installed it, and Microsoft couldn't wait for the next scheduled cycle to fix them.

The announcement lives in Windows Message Center message #4986 under the heading "Take Action: Out-of-band update released to address issues from the September 2026 Windows security update." Not a headline anyone wants to see.

The Three Breakages

The first, and by far the most annoying, hit Remote Desktop Services. RDS would simply stop responding on affected systems, which blocks new remote sessions and can in some cases prevent local and remote sign-ins altogether. It doesn't just break the desktop either. The Microsoft Management Console, RDS Licensing Diagnoser, File Explorer, and even the Windows Update page could go unresponsive alongside it. Microsoft says the failures on Windows Server came from the September patches KB5122871 (Windows Server 2025) and KB5122882 (Windows Server 2022).

The second problem was quieter but annoying for virtualization admins. Hyper-V host folder sharing broke in Linux virtual machines that run through the Host Compute Service. When you share Windows host folders with a Linux guest over Plan9, the folders either don't show up at all or become inaccessible. That's a real pain for anything relying on that data path.

The third is the one that didn't actually get fixed. Some USB Audio Class 1.0 devices fall over when you switch them to multichannel modes, including 8-channel and 3D audio. They still work fine in standard stereo. But this OOB update only partially addressed the audio mess, which brings us to the part that IT teams will care most about.

What's Still Broken

Microsoft is upfront about the gap. The release notes, say plainly that the emergency updates "do not resolve all of the USB audio problems introduced by the September updates."

That leaves Code 10 errors in Device Manager, no audio output, frozen or zeroed volume controls, and sound settings that won't respond. The devices aren't dead. They just behave badly whenever you push them past stereo. Microsoft says it is still "working on a fix" for the remaining audio problems, so don't expect the last piece to land for a while.

The update does bring real security improvements along for the ride. It closes CVE-2026-62721, an Elevation of Privilege flaw in the Windows User-Mode Power Service, across Windows 11 26H1, 25H2, and 24H2. For 26H1 alone, it also patches CVE-2026-85921. You could argue the security fixes make the whole exercise worth the reboot.

Keep in mind how this ships. For current Windows 11 (26H1, 25H2, 24H2) the OOB is a security update, so it installs automatically through Windows Update and Windows Update for Business per your configured policies, and also flows through the Microsoft Update Catalog and WSUS. It's cumulative, meaning it includes everything from the September 8 patch, so there's no staging to worry about. Hotpatch-enrolled 25H2 and 24H2 devices get it restartlessly via KB5129241.

If you're running Windows 11 23H2 or Windows 10 22H2 under ESU, treat this one as an optional non-security update. You'll need to go to Settings > Windows Update > Check for updates > Download and install, or grab it straight from the Catalog. Windows 11 22H2 reached end of servicing, so there's no OOB package for it. The list of KB numbers stretches across Windows Server 2025, Windows Server 2022, and several LTSC and LTSB flavors of Windows 10, but the three current Windows 11 channels cover most shops.

For admins who couldn't wait for the permanent fix, Microsoft's interim guidance was about as bad as it gets. An uninstall of the September security update would restore Remote Desktop functionality, but it also threw away the security fixes from that patch. That's a genuine trade-off. A Group Policy mitigation was also offered while the real fix was being built, so some enterprises managed the gap without gutting their own defenses.

The timing of all this is worth a second glance. Right alongside the OOB notice, Microsoft pushed a 30-day reminder that Windows 11 24H2 (Home/Pro) and Windows 10 Enterprise LTSB 2016 reach end of updates on October 13, 2026. Windows Server 2022 hits mainstream support end on that same date, with the October update being its last mainstream release. So if a machine on that path also caught the RDS breakage, you have a tighter clock than you'd like.

Head here for an overview of the updates. Install the right KB for your channel, and if you have USB multichannel audio on Windows 11, hold your breath until Microsoft ships the follow-up.