Microsoft releases out-of-band Windows 11 update to fix audio and security bugs

The audio problem affected USB Audio Class 1.0 devices, which rely on an older, legacy audio driver that dates to Windows 98, according to ZDNet. Users with those devices could lose audio output entirely, find sound settings unresponsive or unavailable, see volume controls stuck at zero or unresponsive, or encounter a Device Manager error reading “This device cannot start (Code 10).” Before the patch, the only workaround was to change the audio device from 8-channel or 3D audio to standard stereo mode, ZDNet reported.

The glitch did not appear on its own. It arrived with Microsoft’s Sept. 8 security update, ZDNet reported. Monthly updates are intended to fix security bugs and other issues, but they can introduce new problems. In this case, only older devices were affected. Most current audio devices connect through the newer USB Audio Class 2.0 standard, a regular audio jack or Bluetooth, according to ZDNet. The bug was serious enough for Microsoft to issue an out-of-band patch, which the company does when a fix cannot wait for the next regular round of Windows updates.

Beyond the audio issue, the patch addresses a few security flaws and other problems. One vulnerability, CVE-2026-62721, could allow a remote attacker to gain system-level privileges on an unpatched computer, ZDNet reported. Another, CVE-2026-85921, could let someone elevate privileges locally to access files and personal data that would otherwise be secure and protected. A third glitch affects Microsoft’s Remote Desktop Services. That bug, also added with the Sept. 8 Patch Tuesday rollout, could make RDS unstable, cause login failures or render back-end servers unresponsive, according to ZDNet.

The patch also fixes a bug in Microsoft’s Hyper-V virtual machine platform. In that case, applications using HCS-managed virtual machines ran into issues when sharing the host folder with Linux virtual machines using the open-source Plan 9 operating system from Bell Labs, ZDNet reported.

To get the update, users should go to Settings and select Windows Update, ZDNet reported. On Windows 11 26H2, the update is labeled “2026-09 Security Update (KB5129195).” On Windows 11 25H2 or 24H2, it is labeled “2026-09 Security Update (KB5129194).” If the update appears, users can click to download and install it. If it does not, they can check for updates and the correct version should appear, according to ZDNet.

Editor's Summary Microsoft’s out-of-band Windows 11 update fixes a legacy USB audio bug and other issues introduced by the Sept. 8 update, including security vulnerabilities and problems with Remote Desktop Services and Hyper-V. The patch is available through Windows Update for versions 26H2, 25H2 and 24H2. It restores audio for affected legacy USB devices and addresses flaws that could allow privilege escalation or remote system access.