Applies To
Windows Server, version 23H2

Release Date:

9/9/2025

Version:

OS Build 25398.1849

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 more 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 security update contains fixes and quality improvements from KB5063899 (released August 12, 2025). The following summary outlines key issues addressed by this update. Also, included are available new features. The bold text within the brackets indicates the item or area of the change.

  • [App compatibility (known issue)] Fixed: Addresses an issue that caused non-admin users to receive unexpected User Account Control (UAC) prompts when MSI installers perform certain custom actions. These actions might include configuration or repair operations in the foreground or background, during the initial installation of an application.

    This issue could prevent non-admin users from running apps that perform MSI repairs, including Office Professional Plus 2010 and multiple applications from Autodesk (including AutoCAD). This fix reduces the scope for requiring UAC prompts for MSI repairs and enables IT admins to disable UAC prompts for specific apps by adding them to an allowlist. For more information, see Unexpected UAC prompts when running MSI repair operations after installing the August 2025 Windows security update.​​​​​​​

  • [Device management]​​​​​​​ Fixed: An issue where the removable storage policy didn’t correctly block external devices such as USB flash drives. 

  • [File sharing] Fixed: This update addresses an issue where accessing files on a Server Message Block (SMB) share over Quick UDP Internet Connections (QUIC) might result in unexpected delays.

  • [File server] This update enabled auditing SMB client compatibility for SMB Server signing as well as SMB Server EPA. This allows customers to assess their environment and identify any potential device or software incompatibility issues before deploying the hardening measures that are already supported by SMB Server. For detailed guidance, see CVE-2025-55234.

  • [Input]

    • Fixed: This update fixes an issue where using Snap to organize desktop windows could cause the system to stop responding.

    • Fixed: An issue in Desktop Window Manager (uDWM) might cause the screen to stop responding during certain display operations.

    • Fixed: This update addresses an issue with the Chinese (Simplified) Input Method Editor (IME) where some extended characters appeared as empty boxes.

  • [Performance] Improved: Added support for Certificate Revocation List (CRL) partitioning in Windows Certificate Authorities.

If you've already installed previous updates, your device will download and install only the new updates included in this package.

For more information about security vulnerabilities, see the Security Update Guide and the September 2025 Security Updates. 

Windows Server, version 23H2 servicing stack update (KB5065764) - 25398.1840

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

Microsoft is not currently aware of any issues with this update.

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 5065425.

For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5065764) - version 25398.1840. 

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