This security update for Windows 11, version 26H1 (KB5079466), includes the latest security improvements, along with non-security updates from last month’s optional preview release. To learn more about differences between security updates, optional non-security preview updates, Out-of-band (OOB) updates, and continuous innovation, see Windows monthly updates explained. For information on Windows update terminology, see the different types of Windows software updates.
To view the latest updates about this release, visit the Windows release health dashboard or the update history page for Windows 11, version 26H1.
Announcements and messages
This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.
Change log
| Change date | Change description |
|---|---|
| May 26, 2026 | Updated commands (MSU strings) under Catalog. |
| March 11, 2026 | Update: This March 2026 security update (KB5079466) includes the following: [Secure Boot] With this update, Windows quality updates include additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Devices receive the new certificates only after demonstrating sufficient successful update signals, maintaining a controlled and phased rollout. |
Improvements
This security update contains fixes and quality improvements from KB5077239 (released February 10, 2026). 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.
- [Secure Boot] With this update, Windows quality updates include additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Devices receive the new certificates only after demonstrating sufficient successful update signals, maintaining a controlled and phased rollout.
- [Windows Defender Application Control] Improved: This update improves how Windows Defender Application Control (WDAC) handles COM objects allowlisting policies. COM objects were blocked when the endpoint security policy was set higher than the allowlisting policy. With this update, COM objects are allowed as expected.
- [Windows System Image Manager] Improved: This update improves the reliability of choosing trusted catalog files. It adds a warning dialog that helps you confirm that the file you select comes from a trusted source.
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 March 2026 Security Updates.
AI Components
This release updates the following AI components:
| AI Component | Version |
|---|---|
| Image Search | 1.2601.1268.0 |
| Content Extraction | 1.2601.1268.0 |
| Semantic Analysis | 1.2601.1268.0 |
| Settings Model | 1.2601.1268.0 |
Windows 11 servicing stack update (KB5078262)- 28000.1638
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 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 | |
|---|---|---|
|
This update downloads and installs automatically from Windows Update and Microsoft Update. |
Note
- If you want to remove the LCU
- Before you decide to remove the LCU, see Understanding the risks: Why you should not uninstall security updates.
- 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 5079466.
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5078262) - version 28000.1638.