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Release Date:



OS Build 25398.950

For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. For an overview of Windows Server, version 23H2, see its update history page.      


This security update includes quality improvements. When you install this KB: 

  • New! This update affects Server Message Block (SMB) over Quick UDP Internet Connections (QUIC). It turns on the SMB over QUIC client certificate authentication feature. Admins can use it to restrict which clients can access SMB over QUIC servers. To learn more, see Configure SMB over QUIC client access control in Windows Server.

  • This update affects the version of curl.exe that isin Windows. The version number is now 8.7.1.

  • This update addresses an issue that affects lsass.exe. It stops responding. This occurs after you install the April 2024 security updates on Windows servers.

  • This update addresses an issue that affects Microsoft Edge. The UI is wrong for the Internet Options Data Settings.

  • This update affects the Antimalware Scan Interface (AMSI) AmsiUtil class. It helps to detect the bypass of the AMSI scan. This update also addresses some long-term issues that expose your device to threats.

  • This update addresses an issue that affects Storage Spaces Direct (S2D) and Remote Direct Memory Access (RDMA). When you use them with SMBdirect in your networks, the networks fail. You also lose the ability to manage clusters.

  • This update addresses an issue that affects dsamain.exe. It stops responding. This occurs when the Knowledge Consistency Checker (KCC) runs evaluations.

  • This update addresses an issue that affects Enhanced Fast Reconnect. It fails. This occurs when you use it with third-party remote desktop protocol (RDP) providers.

  • This update addresses an issue that affects lsass.exe. It leaks memory. This occurs during a Local Security Authority (Domain Policy) Remote Protocol (LSARPC) call.

  • Starting in this update, File Explorer adds the Mark of the Web (MoTW) tag to files and folders that come from untrusted locations. When MapUrlToZone classifies a file as “Internet,” that file also gets this tag. Because of this change, the “LastWriteTime” time stamp is updated. This might affect some scenarios that rely on file copy operations.​​​​​​​

For more information about security vulnerabilities, please refer to the Security Update Guide and the June 2024 Security Updates

Windows Server, version 23H2 servicing stack update (KB5039331) - 25398.940

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.

Known issues in this update



After installing this update, you might see an issue on cloud-based SQL servers where Azure Synapse SQL Serverless Pool databases go on “Recovery pending” state. This issue is more likely to affect environments utilizing Customer-Managed Key (CMK) and Azure Synapse dedicated SQL pool.

This issue is addressed in KB5040438.

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.


Next Step


None. This update will be downloaded and installed automatically from Windows Update and Microsoft Update.


Next Step


None. This update will be downloaded and installed automatically from Windows Update for Business in accordance with configured policies.


Next Step


To get the standalone package for this update, go to the Microsoft Update Catalog website.


Next Step


This update will automatically sync with Windows Server Update Services (WSUS) if you configure Products and Classifications as follows:

Product: Microsoft Server operating system-21H2

Classification: Security Updates

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 that are provided in this update, download the file information for cumulative update 5039236.

For a list of the files that are provided in the servicing stack update, download the file information for the SSU (KB5039331) - version 25398.940

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