Win Update KB5124008 Windows 11 Cumulative Update build 26100.9445 (24H2) and 26200.9445 (25H2) - Sept. 8

Announcements and messages​

This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.

Windows Secure Boot certificate expiration

Important

Secure Boot certificates used by most Windows devices started to expire on June 2026. Microsoft has been updating these certificates on PCs and non-managed business devices for the past months. Devices that haven't received the newer certificates will continue to start, and standard Windows updates will continue to install. We will continue to install the newer certificates via Windows updates in the coming months.

End of updates

Windows 11, version 24H2 Home and Pro editions will reach end of updates on October 13, 2026. Devices running these editions will no longer receive fixes for known issues, time zone updates, technical support, or monthly security and preview updates containing protections from the latest security threats. Enterprise and Education editions remain supported until October 12, 2027.

To stay protected and up to date, we recommend you upgrade to the latest version of Windows 11.

Improvements​

This update includes improvements from the following previously released updates:

• August 27, 2026-KB5120998 (OS Builds 26200.9278 and 26100.9278)

The following summary outlines key quality improvements addressed by this update. The bold text within the brackets indicates the item or area of the change.

• [Security updates] This update provides security improvements. For more information about the security vulnerabilities resolved by this update, see the Security Update Guide)
• [Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
• [Mouse] Fixed: This update addresses an issue that prevented customized mouse cursor settings, including pointer style and color, from displaying correctly. Selected cursor options and colors now work as expected.
• [Personalization] Fixed: This update addresses an issue where desktop background and other personalization settings might not load correctly, causing the desktop background to appear black.
• [Teams and Outlook on Arm64 PCs] Fixed: This update addresses an issue that could cause Microsoft Teams and Microsoft Outlook to unexpectedly close on Arm64-based PCs.
• [Date and Time] This update adjusts Morocco Standard Time to reflect Morocco's transition to permanent UTC+00:00 effective September 20, 2026. This change ensures that the correct local time is displayed after the transition.
• [Remote Desktop Audio Redirection] This update addresses an issue affecting Remote Desktop audio redirection that could prevent audio from a remote session from playing on the local device in certain configurations.
• [OMA-DM Client Logging] This update improves diagnostic logging for the OMA-DM client, providing additional information to help troubleshoot device management server connection issues.

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

Components updates​

AI components

This release updates the following AI components to version 1.2608.951.0: Image Search, Content Extraction, Semantic Analysis, and Settings Model. To learn more, see Release information for AI components.

Servicing stack update

Includes KB5124007 (Build 26100.9441), which improves the reliability of the Windows update installation process. 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 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.

Deployment

If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.

Note: The boot.stl file is used during Secure Boot validation and must match the Windows version and architecture of the image you are updating.
To ensure the boot.stl file is included as part of the installation media, do one of the following:

• Use the Update WinPE script to update an existing Windows image. (Recommended)
• Manually copy the boot.stl file from the device Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.

For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.

Install this update​

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

File information​

For a list of the files provided in this update, download the file information for cumulative update KB5124008.

For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5124007) - version 26100.9441.





Check Windows Updates


UUP Dump:

64-bit ISO download:

ARM64 ISO download: