Windows 11 KB5121003, KB5121000 & KB5120240 August 2026 Patch Tuesday Updates Released

It’s the second Tuesday of the month, which means Patch Tuesday has arrived for Windows 11 users. Microsoft has now released its August 2026 Patch Tuesday updates across several supported Windows 11 versions. The latest security updates cover Windows 11 23H2, 24H2, 25H2, and 26H1. Microsoft has also included important security improvements and further work around Secure Boot certificates.

Windows 11 24H2 and 25H2 Get KB5121003

For Windows 11 24H2 and 25H2, Microsoft has released KB5121003. The update moves both versions to OS Build 26100.9168 and 26200.9168, respectively. Microsoft says the package includes security improvements alongside additional Secure Boot changes. The company is expanding device targeting data for PCs eligible to receive new Secure Boot certificates automatically. Certificate deployment will continue through Windows Update across supported consumer PCs and eligible non-managed business devices.

Windows 11 26H1 Gets KB5121000

Moving on, users on Windows 11 26H1 receives KB5121000 as August 2026 Patch Tuesday update, bringing the operating system to OS Build 28000.2704. Microsoft says this update addresses 421 Microsoft CVEs. It also improves TPM maintenance reporting by ensuring EK certificate status is reported accurately.

The update also expands Secure Boot certificate targeting coverage. Microsoft says certificate deployment will continue across supported devices over the coming months.

Windows 11 23H2 Gets Several Quality Improvements

Windows 11 23H2 receives KB5120240, which brings the operating system to OS Build 22631.7517. This package includes several quality improvements beyond security changes. Microsoft has refreshed the COSA profile for SolNet-Mobile to support newer operator settings. The update also improves reliability for devices managed through MDM when an MDM certificate expires.

File History is receiving attention too. Microsoft says backups to SMB network shares should now be more reliable during scheduled operations. The emoji panel also gets a notable change. Windows 11 23H2 now supports GIPHY after Google’s Tenor API was deprecated.

Microsoft is also continuing its Secure Boot certificate rollout across supported Windows devices. Users who already installed earlier updates will only receive the new components included in these packages. Last but not least, Windows 10 users are also getting August 2026 security patch under KB5120249.