September 9, 2025—KB5065432 (OS Build 20348.4171)
Applies To
Release Date:
9/9/2025
Version:
OS Build 20348.4171
Windows Secure Boot certificate expirationWindows Secure Boot certificate expiration and CA updates.
Important: 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, seeÂTo 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 2022.   Â
Stay informed! Follow @WindowsUpdate for the latest updates from the Windows Release Health Dashboard.  Â
Improvements
This security update contains fixes and quality improvements from KB5063880 (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.
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[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.Unexpected UAC prompts when running MSI repair operations after installing the August 2025 Windows security update.
For more information, see -
[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.
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[Input]Â Fixed: This update addresses an issue with the Chinese (Simplified) Input Method Editor (IME) where some extended characters appeared as empty boxes. Â
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[Performance]​​​​​​​ Fixed: This update addresses an issue where a single, oversized Certificate Revocation List (CRL) file slows down system performance. To improve speed and privacy, the system now plans to use smaller, partitioned CRLs.
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, please refer to the Security Update Guide and the September 2025 Security Updates.
Windows Server 2022 servicing stack update (KB5065769) - 20348.4160
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​​​​​​​
​​​​​​​Symptoms KB5065306) or the September 2025 security update (KB5065432). These devices may experience failures with PowerShell Direct (PSDirect) connections when the host and guest virtual machines (VMs) are both not fully updated. When a patched guest VM attempts to connect to an unpatched host (or vice versa), the system is expected to fall back to a legacy handshake and clean up the socket gracefully. However, this fallback mechanism fails intermittently, resulting in socket cleanup issues. The connection failure might appear random, and users might observe Event ID 4625 logged in the Security Event log within Windows Event Viewer. ​​​​​​​
We are aware of an edge case affecting hotpatched devices that have installed the September 2025 Hotpatch update (WorkaroundÂ
This issue is addressed in KB5066359. If your hotpatched device is experiencing issues with PSDirect connection, we recommend updating both the host and guest VM with these updates.
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.
Prerequisite for offline OS image servicing:
​​​​​​​Make sure that your image includes KB5030216 (09/12/2023) or a later LCU. If not, install it on your offline media before you install the latest update. This LCU updates the SSU version to 20348.1960. That is the minimum SSU version you must have to prevent error 0x800f0823 (CBS_E_NEW_SERVICING_STACK_REQUIRED).
Install this update
To install this update, use one of the following Windows and Microsoft release channels.
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This update downloads and installs automatically from Windows Update and Microsoft Update. |
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This update downloads and installs automatically from Windows Update for Business in accordance with configured policies. |
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To get the standalone package for this update, go to the Microsoft Update Catalog website. |
1 This latest cumulative update includes updates for AI components. Even though the AI component updates are included in the update, the AI components are only applicable to Windows Copilot+ PCs and will not install on Windows PC or Windows Server.
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This update automatically syncs 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 provided in this update, download the file information for cumulative update 5065432​​​​.Â
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5065769) - version 20348.4160.Â