Windows Server · 2025 · Release · Out-of-band update

September 14, 2026—KB5129235 (OS Build 26100.33451) Out-of-band

Windows Server 2025: LTSC mainstream support through 2029-11-13

Microsoft release information · Verified Nov 12, 2026

All 2025 builds JSON — this build from the builds API

Microsoft's known issues — KB5129235

  • Issue Known issue After installing KB5070881 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287 . After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms: The device displays an error in Device Manager: "This device cannot start (Code 10).” No audio output. Volume controls are unresponsive or remain at zero. Sound settings are unresponsive or unavailable. Some devices might Workaround: This issue is partially resolved in the out-of-band (OOB) update released on September 14, 2026. This OOB update resolves the symptoms experienced on devices using 8-channel or 3D audio modes. Microsoft is working to address the other symptoms and will provide more information when it is available. IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.

Microsoft's release notes for KB5129235 ›

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