KB5078136 (OS Build 20348.4651) Out-of-Band Update for Windows Server 2022 - January 24, 2026

Summary

This is a cumulative out-of-band (OOB) update for Windows Server 2022, released on January 24, 2026, producing OS Build 20348.4651. It incorporates all prior security fixes and adds a targeted quality improvement to resolve a file-system regression introduced by the January 13, 2026 security update. See Microsoft Support for the official page.

Improvements and fixes

• File System regression fix: After installing Windows updates released on or after January 13, 2026, some applications became unresponsive or returned unexpected errors when opening or saving files to cloud-based storage providers such as OneDrive or Dropbox. In certain Outlook configurations where PST files are stored on OneDrive, Outlook could hang and fail to reopen without terminating the process or restarting the system. Users could also experience missing Sent Items or previously downloaded emails being downloaded again. This update resolves that regression.
• This update is cumulative and also includes all security fixes and improvements from the January 13, 2026 security update (KB5073457) and the January 17, 2026 out-of-band update (KB5077800).
• A bundled servicing stack update (SSU KB5074428, version 20348.4640) is included, delivering quality improvements to the component responsible for installing Windows updates.

Known issues

WSUS does not display synchronization error details

Symptom: After installing KB5070884 or later updates, Windows Server Update Services (WSUS) no longer displays synchronization error details within its error reporting interface.

Workaround: This functionality was temporarily removed to address the Remote Code Execution vulnerability CVE-2025-59287. Microsoft has not listed an alternative workaround beyond this explanation at this time.

Some devices with Virtual Secure Mode enabled may fail to shut down or hibernate

Symptom: After installing this update, some Secure Launch-capable PCs with Virtual Secure Mode (VSM) enabled are unable to shut down or enter hibernation. The device restarts instead of completing the requested power state transition.

Workaround: This issue is addressed in KB5075906. Install that update to resolve the problem.

How to get this update

Microsoft now bundles the latest servicing stack update (SSU) together with the latest cumulative update (LCU) in a single package. Before installing, note that the SSU cannot be removed from the system after installation, and running wusa.exe /uninstall on the combined package will not work for that reason.

This update is available through the following channels:

• Windows Update / Windows Update for Business - listed as available; refer to the Microsoft Update Catalog for the standalone package.
• Microsoft Update Catalog - the standalone package for KB5078136 can be downloaded directly from the Catalog. Note that this update includes AI component updates, but those components apply only to Windows Copilot+ PCs and will not install on standard Windows PCs or Windows Server.
• Windows Server Update Services (WSUS) - available; refer to the Catalog option.

To remove only the LCU after installation, use the DISM /Remove-Package command with the LCU package name as the argument. Find the package name first by running DISM /online /get-packages.

Frequently asked questions

Why was this update released out-of-band rather than waiting for the next Patch Tuesday?

Microsoft issued this OOB update to address a specific file-system regression, introduced on January 13, 2026, that caused applications to hang or fail when accessing cloud storage such as OneDrive or Dropbox. The severity of that regression, particularly its impact on Outlook with PST files on OneDrive, warranted an immediate fix rather than holding it until the next scheduled release.

Does this update replace previous January 2026 updates, or do I need to install them first?

This update is cumulative, so it incorporates all fixes from the January 13, 2026 security update (KB5073457) and the January 17, 2026 OOB update (KB5077800). Devices that already have those updates installed will only download the new content added in this package.

What should I do if devices are restarting instead of shutting down or hibernating after this update?

This behavior affects Secure Launch-capable machines with Virtual Secure Mode enabled. Microsoft has confirmed a resolution is available in KB5075906. Install that update to correct the unexpected restart behavior on affected devices.

Can I uninstall this update if it causes problems in my environment?

You can remove the LCU portion using DISM /Remove-Package with the appropriate package name, which you can retrieve by running DISM /online /get-packages. However, because the servicing stack update (SSU KB5074428) is bundled in the same package, the SSU component cannot be removed after installation.