Microsoft Addresses Remote Desktop Failures and Other Issues with Out-of-Band Windows Update
Microsoft has released an out-of-band update to resolve critical issues with Remote Desktop Services, shared folder access in Linux VMs, and USB audio devices, which were introduced by earlier September security patches.
Microsoft has issued an out-of-band Windows update on September 14, 2026, to rectify several significant problems that emerged following its September 8 security patches. The update specifically targets failures in Remote Desktop Services (RDS), issues preventing shared folders from appearing in Linux virtual machines, and audio malfunctions affecting certain USB devices. Additionally, specific versions of Windows 11 are receiving targeted security fixes for elevation-of-privilege vulnerabilities.
The most disruptive of these issues involved Remote Desktop Services. After the September security update, administrators and users experienced a range of problems, including the inability to establish RDP connections, sign-in rejections, and systems becoming unresponsive during RDS configuration. Furthermore, critical management tools such as the Microsoft Management Console, RDS Licensing Diagnoser, File Explorer, and even the Windows Update page could cease to function. Microsoft has clarified that these specific RDS problems do not impact Windows 365 or Azure Virtual Desktop environments, helping to differentiate them from other potential remote access disruptions.
The update also addresses a critical bug affecting Hyper-V environments, particularly those using applications that rely on Windows Host Compute Service for managing virtual machines. While these applications could successfully launch Linux guests, users encountered failures when attempting to access or display host folders shared via the Plan9 protocol. Microsoft has identified Windows Subsystem for Linux and Claude Cowork as examples of affected applications. Standard Hyper-V virtual machines that do not utilize Plan9 sharing are not impacted by this particular issue.
For users experiencing problems with USB Audio Class 1.0 devices, the update provides a more focused fix. It aims to restore multichannel audio operations, including support for eight-channel and 3D audio modes. However, Microsoft has cautioned that this release may not resolve all reported USB audio failures, and separate issues such as Code 10 errors, missing sound, or unresponsive volume controls might persist. Users are advised to consult Microsoft's documentation for a comprehensive understanding of the scope of the USB audio fix.
Beyond the reliability fixes, the update also incorporates security enhancements for specific Windows 11 versions. For Windows 11 versions 25H2 and 24H2, update KB5129195 raises the OS build to 26200.9457 and 26100.9457, respectively. This update includes a fix for CVE-2026-62721, an elevation-of-privilege vulnerability within the Windows User-Mode Power Service. Similarly, Windows 11 version 26H1 receives KB5129194, updating its build to 28000.2956 and patching the same elevation-of-privilege flaw. Additionally, the 26H1 package addresses CVE-2026-85921, another elevation-of-privilege vulnerability affecting the Windows Secure Kernel Mode.
Microsoft offers different installation paths for these updates depending on the Windows edition and update channel. For eligible Windows 11 25H2 and 24H2 devices enrolled in hotpatching, KB5129241 is available and can be applied without a restart if the September security update is already installed. This hotpatching mechanism aligns with Microsoft's established procedures for out-of-band updates. The security packages for Windows 11 26H1, 25H2, and 24H2 are designed to install automatically via Windows Update, subject to organizational policies, and are also accessible through the Microsoft Update Catalog and Windows Server Update Services.
For Windows 11 version 23H2, an optional update, KB5129242, has been released. Administrators who download standalone packages are reminded to adhere to Microsoft's specified installation order, including any necessary checkpoint updates, to ensure successful deployment. This multi-faceted update underscores Microsoft's commitment to rapidly addressing critical issues that impact system stability and security, even outside of its regular Patch Tuesday schedule.