Microsoft has released Windows 11 KB5066835 and KB5066793 cumulative updates for versions 25H2/24H2 and 23H2 to fix security vulnerabilities and issues.
Today's updates are mandatory as they contain the October 2025 Patch Tuesday security patches for vulnerabilities discovered in previous months.
You can install today's update by going to Start > Settings > Windows Update and clicking on 'Check for Updates.'
You can also manually download and install the update from the Microsoft Update Catalog.
This is the first 'Patch Tuesday' release for version 25H2, but as it's based on version 24H2, there are no exclusive or special changes. You'll get the same fixes across the two versions of Windows 11.
What's new in the October 2025 Patch Tuesday update
After installing today's security updates, Windows 11 25H2 (KB5066835 ) will have its build number changed to Build 26200.6899 (or 26100.6899 in case of 24H2), and 23H2 (KB5066793 ) will be changed to 226x1.6050.
It is worth noting that this is the second last update for Windows 11 23H2 as the operating system's support ends in November 2025.
Here's the full list of improvements applicable to version 24H2 and 25H2:
[Browser] Fixed: This update addresses an issue that caused the print preview screen to stop responding in Chromium-based browsers.
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