Windows 11 KB5121003 & KB5120240 cumulative updates released

Microsoft has released Windows 11 KB512103 and KB5120240 cumulative updates for versions 25H2/24H2 and 23H2 to fix security vulnerabilities, bugs, and add new features.

Today's updates are mandatory as they contain the August 2026 Patch Tuesday security patches for 400 vulnerabilities discovered in 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 eighth 'Patch Tuesday' release in 2026, and it's based on 24H2, which means 25H2 gets the same update. There are no exclusive or special changes. You'll get the same fixes across the two versions of Windows 11.

With today's update, Microsoft is making Windows better at typos and rolling out multiple performance-related fixes, but the catch is that most changes don't show up right away.

Here's the full list of improvements and fixes:

File sizes in the Details view now display using appropriate units (KB, MB, GB) instead of KB-only, making them easier to understand at a glance.

Middle click to open a folder in a new tab is now supported in the Address Bar and the page for a more consistent and efficient tabbed experience across File Explorer.

This update eliminates a grey flash on load and unexpected scrolling to the top on the page in certain cases.

This update improves the appearance of file thumbnails in the Recommended section on the page so they’re crisper and easier to read.

This update improves app to better handle typos and partial app names when finding installed apps.

This update improves Settings relevance to surface more useful settings higher in results.

New! This update adds Voice Isolation to Voice Access, helping it better recognize your voice by reducing interference from other speakers and background noise. Voice Access now offers three speed recognition modes under Voice Access settings > Improve speech recognition:

Voice Isolation — Filters out other speakers and background noise (one-time voice setup required).

Remove background noise only — Filters out non-speech sounds like typing or door slams. No additional setup needed.

No filtering — Default microphone input with no additional processing.

To set up Voice Isolation, go to Voice Access settings > Improve speech recognition and select Voice Isolation .

New ! This update adds Korean language support for voice access.

This update improves the realiability of starting Voice Access.

New ! New gesture controls for precision touchpads are available in Settings > Bluetooth & devices > Touchpad :

Scroll and zoom speed — Adjust the baseline speed for scroll and zoom gestures.

Accelerated scrolling — Scroll faster the more you repeat the gesture, so you can move quickly through long documents.

The update improves the reliability of Start view preferences, ensuring your selected view is retained.

This update improves keyboard when keyboard focus was set to the apps list within Start .

This update restores support for Unicode variation sequences in the Myanmar Text font.

This update improves character shaping and rendering for Mongolian Baiti font, providing more accurate and consistent text display.

This update improves calculation of update progress progression in Windows Update Settings.

This update includes changes to update clean-up logic to improve system performance immediately following an update.

This update improves detection for triggering time zone change notifications.

This update improves daylight saving time (DST) data accuracy for Middle East Standard Time (Beirut), Morocco Standard Time (Casablanca), Israel Standard Time (Jerusalem), and Greenland Standard Time (Nuuk).

Microsoft is not aware of any new issues with this month's Patch Tuesday, but we'll update the article if we come across major problems.

Overall prevention scores can hide what happens after initial access. Once attackers are using valid credentials, prevention drops sharply.

The Blue Report 2026 measures defenses technique by technique across 338 million simulations run in customer production environments.