The September 2026 security update is now available for all supported versions of Windows. We recommend that you install these updates promptly. Information about the contents of this update is available in the release notes, which are accessible from the Windows 11 update history page. For instructions on how to install this update on your home device, see the Update Windows article. To learn more about the different types of monthly quality updates, see Understanding Windows monthly updates. To stay informed about the latest updates and releases, follow @WindowsUpdate on X.
Microsoft 365 Message Center ID: MC1469327
Last Modified: September 9, 2026
Category: Message Center
Tags: New feature
Status: Launched
Products & Platforms: Windows
Highlights for the Windows 11, version 25H2 update:
- This security update includes improvements that were part of update KB5120998 (released August 27, 2026).
- This update expands 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.
- This update makes quality improvements to the servicing stack, which is the component that installs Windows updates.
Short on time? Watch the Windows 11 release notes video for this month’s tips.
Note: With recent and upcoming Windows updates over the next few months, a limited number of consumer and business devices might experience one additional restart during installation. This one‑time restart occurs after a Secure Boot certificate update is applied as part of the Secure Boot update process.