Microsoft’s October Windows Updates Break Remote Desktop Services

Microsoft released an out-of-band Windows update on September 14, 2026, to fix problems introduced by its September 8 security updates.

The release addresses Remote Desktop Services failures, missing shared folders in Linux virtual machines, and audio errors affecting some USB devices. Selected Windows 11 versions also receive additional security fixes.

The update covers multiple Windows client and server releases, but installation requirements differ. Standard cumulative packages include earlier security fixes, while the hotpatch package requires installing the September security update first.

Microsoft’s release notes also warn that the update does not resolve every reported USB audio problem.

Microsoft Remote Desktop Issues

Remote Desktop Services caused some of the most disruptive failures. After the September security update, affected systems could lose RDP connections, reject sign-ins, or become stuck during Remote Desktop configuration.

Microsoft Management Console, RDS Licensing Diagnoser, File Explorer, and the Windows Update page could also stop responding. These signs match the disruption covered in Cyber Security News’ report on September Windows Server Remote Desktop failures.

Microsoft says the September issue does not affect Windows 365 or Azure Virtual Desktop, helping administrators separate this problem from other remote access failures.

The Hyper-V fix targets applications using virtual machines managed through Windows Host Compute Service. These applications could start Linux guests normally, yet fail to display or access host folders shared through Plan9.

Microsoft identifies Windows Subsystem for Linux and Claude Cowork among affected applications. Standard Hyper-V virtual machines that do not use Plan9 sharing are unaffected.

USB Audio Class 1.0 devices receive a narrower fix. The update restores multichannel operation, including eight-channel and 3D audio modes.

However, Microsoft still lists separate problems involving Code 10 errors, missing sound, and unresponsive volume controls. Users should not assume this release fixes every USB audio failure.

For Windows 11 versions 25H2 and 24H2, KB5129195 raises OS builds to 26200.9457 and 26100.9457. It also fixes CVE-2026-62721, an elevation-of-privilege vulnerability in Windows User-Mode Power Service.

Windows 11 version 26H1 receives KB5129194, bringing its build to 28000.2956 and addressing the same flaw. The 26H1 package additionally fixes CVE-2026-85921, an elevation-of-privilege vulnerability in Windows Secure Kernel Mode. These security changes are separate from the reliability fixes for Remote Desktop, shared folders, and audio.

Eligible Windows 11 25H2 and 24H2 devices enrolled in hotpatching receive KB5129241. Microsoft says it applies without a restart when the September security update is already installed.

Cyber Security News’ earlier coverage of Windows 11 out-of-band hotpatch updates explains this separate update path.

The security packages for Windows 11 26H1, 25H2, and 24H2 install automatically through Windows Update, subject to configured business policies. They are also available through the Microsoft Update Catalog and synchronize with Windows Server Update Services.

Windows 11 23H2 receives optional KB5129242 instead. Administrators downloading standalone packages should follow Microsoft’s installation order for any required checkpoint updates.

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