Microsoft has released Windows 11 Cumulative Updates KB5021255 and KB5021234 for builds 22H2 and 21H2 to fix security vulnerabilities and resolve twenty-nine bugs and performance issues.

KB5021255 and KB5021234 are mandatory cumulative updates because they contain the December 2022 Patch Tuesday Security Updates for vulnerabilities discovered in previous months.

These security updates include a fix for a actively exploited vulnerability which bypassed Mark of the Web security warnings. Threat actors exploited the flaw in malware distribution campaigns that installed ransomware on Windows devices.

Windows 11 users can install today’s update by going to Begin > Settings > Windows Update and clicking on ‘Check for updates.’

Windows 11 users can also manually download and install the update from the Microsoft Update Catalog.

What’s New in Windows 11 KB5021255 Update

After installing today’s non-security update, Windows 11 22H2 (KB5021255) will have its build number replaced by 22621.963and 21H2 (KB5021234) will be replaced by 22000.1335.

Windows 11 Cumulative Updates include 29 improvements and fixes, with the nine highlighted fixes listed below:

• New! This update addresses a known issue that may affect Task Manager. It may display some User Interface (UI) elements in unexpected colors. Some parts of the user interface may not be readable. This issue can occur if “Choose your mode” is set to “Custom” in the Personalization > Colors section of the settings.

• New! Microsoft OneDrive subscribers will now see storage alerts on the Systems page of the Settings app. Alerts appear when you approach your storage limit. You can also manage your storage and buy more storage if needed.

• New! It’s now easier to see the total amount of storage capacity for your OneDrive subscriptions. Total storage appears on the Accounts page of the Settings app.

• New! For Windows Spotlight, we combined them with Themes on the Personalization page. This makes it easier for you to discover and activate the feature.

• Fixes an issue that prevents some modern apps from opening.

• It fixes an issue that may cause some applications to become unresponsive when using the File Open dialog box.

• For those of you using the Input Method Editor (IME), Microsoft is addressing a known issue that may cause some applications to become unresponsive. This happens when you use hotkeys to change the input mode of the IME.

• If you noticed that File Explorer stopped working when you close context menus and menu items, Microsoft has fixed this problem.

• It discusses the suspension of Daylight Saving Time (DST) in the Republic of Fiji for this year.

In addition to these issues, Microsoft has made twenty other changes, as explained in the KB5020044 November Preview Update.