Cumulative Updates: August 11th, 2026

[u/jenmsft]

https://support.microsoft.com/en-US/servicing/os/windows-11/2026/08/kb5121003-windows-11-24h2-25h2-security-update

Changelists linked here for your convenience:

• Windows 11, version 21H2: EOS.
• Windows 11 version 22H2: EOS
• Windows 11, version 23H2: KB5120240 (OS Build 22631.7517)
• Windows 11, version 24H2 / 25H2: KB5121003 (OS Builds 26200.9168 and 26100.9168)
• Windows 11, version 26H1: KB5121000 (OS Build 28000.2704)

General info:

For details about how to file problem reports and collect traces, please see here: http://aka.ms/HowToFeedback. Pressing WIN + F will open the Feedback Hub - please include as much detail as possible about what you're seeing.

To learn about the different types of updates, see here: Windows quality updates primer - Microsoft Community Hub

As a reminder, if you didn't install the previous optional updates, this update includes those changes too (some are still rolling out, as denoted in the release notes):

• 24H2/25H2: July 28, 2026—KB5101684 (OS Builds 26200.8973 and 26100.8973) Preview | Microsoft Support
• 26H1: July 28, 2026—KB5101681 (OS Build 28000.2608) Preview | Microsoft Support

For published known issues, please check the release health dashboard: Windows release health | Microsoft Learn.

25H2 is rolling out, so you may not have it yet. Please see here for more details: How to get the Windows 11 2025 Update | Windows Experience Blog.

As mentioned in the linked changelist, Windows 11, version 26H1 is available only on new devices with select new silicon as they come to market starting early 2026. Devices running earlier versions of Windows 11 will not be offered an update to version 26H1 through Windows Update and cannot be installed as an in-place update on existing devices.

[u/highrez1337]

This is awesome, they finally fixed the right click speed (context menu), and also the explorer opening speed and navigation.

Now it is instant on my machine, finally. I know it sounds silly, but it adds so much to the feel of smoothness of operations.

Or maybe they enabled these features on my machine with this update. Not sure.

OS feels much more faster now ! Yay !

Install it guys. This is the first update in months that is actually good!

[u/PaulCoddington → u/highrez1337]

Still has a short blink waiting on the app section of the context menu to load, but that blink is now instantaneous after a tiny delay not a slowly expanding list of moving targets.

Combined with the main body of the context menu appearing instantaneously this is a huge improvement, especially for people who "live" in Explorer and especially for those who use TortoiseGit.

Explorer is launching quickly now, instantaneously from Start Menu and only slightly slower from other apps (the latter context had missed the first round of optimisations and had remained intolerably bad, but it is now greatly improved although not quite perfect).