Microsoft releases Windows 10 KB5122878 extended security update

Microsoft has released the Windows 10 KB5122878 extended security update, which includes this month's record-breaking September 2026 Patch Tuesday fixes, along with a few bug fixes.

If you are running Windows 10 Enterprise LTSC or are enrolled in the ESU program, you can install this update like normal by going into Settings, clicking on Windows Update, and manually performing a 'Check for Updates.'

After installing this update, Windows 10 will be updated to build 19045.7725, and Windows 10 Enterprise LTSC 2021 will be updated to build 19044.7725.

Microsoft is no longer releasing new features for Windows 10, and the KB5122878 update primarily contains security updates and bug fixes.

The update also includes fixes released as part of today's record-breaking September 2026 Patch Tuesday, which fixed a massive 966 vulnerabilities across Microsoft's products, including two actively exploited zero-day flaws.