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

January 17, 2026—KB5077793 (OS Build 26100.32234) Out-of-band

Windows Server 2025: Current LTSC release

Microsoft's known issues — KB5077793

  • 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 this update, some applications may become unresponsive or encounter unexpected errors when opening files from or saving files to cloud-based storage, such as OneDrive or Dropbox. In certain Outlook configurations that store PST files on OneDrive, Outlook may hang and fail to reopen unless the process is terminated or the system is restarted. Users may also see missing sent Items or previously downloaded emails Workaround: This issue is addressed in KB5078135 .

Microsoft's release notes for KB5077793 ›

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