Applies To
Windows Server, version 23H2

Release Date:

10/23/2025

Version:

OS Build 25398.1916

Windows Secure Boot certificate expirationImportant: Secure Boot certificates used by most Windows devices are set to expire starting in June 2026. This might affect the ability of certain personal and business devices to boot securely if not updated in time. To avoid disruption, we recommend reviewing the guidance and taking action to update certificates in advance. For details and preparation steps, see Windows Secure Boot certificate expiration and CA updates.

To learn about Windows update terminology, see types of Windows updates and monthly quality update types. For an overview, see the update history page for Windows Server, version 23H2.

Improvements 

This out-of-band (OOB) update includes quality improvements. This update is cumulative and includes security fixes and improvements from the October 14, 2025, security update (KB5066780), in addition to the following: 

  • ​​​​​​​​​​​​​​[Windows Server Update Services (WSUS)] Fixed: This update addresses a remote code execution (RCE) vulnerability that was identified in WSUS reporting web services. For more information about the security fix, see CVE-2025-59287.

Windows Server, version 23H2 servicing stack update (KB5066779) - 25398.1906

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.

Known issues in this update​​​​​​​

After installing this update 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.

How to get this update

Before you install this update

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions. 

Install this update

To install this update, use one of the following Windows and Microsoft release channels.

Available

Next Step

Included

This update downloads and installs automatically from Windows Update and Microsoft Update.

If you want to remove the LCU

To remove the LCU after installing the combined SSU and LCU package, use the DISM/Remove-Package command line option with the LCU package name as the argument. You can find the package name by using this command: DISM /online /get-packages.

Running Windows Update Standalone Installer (wusa.exe) with the /uninstall switch on the combined package will not work because the combined package contains the SSU. You cannot remove the SSU from the system after installation.

File Information 

For a list of the files provided in this update, download the file information for cumulative update 5070879.

For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5066779) - version 25398.1906. 

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