Microsoft Releases Windows 11 KB5134133 and KB5134134 Emergency Updates

Microsoft has released two out-of-band updates for Windows 11 to fix certificate trust issues on devices that cannot access its online certificate-update service.

The new updates, KB5134133 and KB5134134, include updated trusted root certificates directly in the cumulative update packages. This allows affected devices to receive certificate trust information without relying on Microsoft’s usual online service.

Unlike most emergency Windows updates, these patches target specific systems rather than regular Windows 11 users.

Windows 11 KB5134133 and KB5134134 target devices with certificate update issues

Microsoft has released the updates for four Windows 11 versions:

• KB5134133 for Windows 11 24H2: Build 26100.9725
• KB5134133 for Windows 11 25H2: Build 26200.9725
• KB5134133 for Windows 11 26H2: Build 26300.9725
• KB5134134 for Windows 11 26H1: Build 28000.3237

The updates primarily target devices operating in disconnected environments, systems with automatic certificate trust list updates disabled, and computers that cannot connect to Microsoft’s certificate-update service.

Windows normally retrieves trusted root certificate information through its online service. However, devices without access to this service may miss certificate trust updates, potentially causing problems when verifying certificates used by websites, applications, and other services.

By including the updated certificates in the cumulative updates, Microsoft provides another way for these systems to maintain their certificate trust information.

Both updates include October 2026 security fixes

KB5134133 and KB5134134 are cumulative updates that include all changes from the October 13, 2026, Windows 11 Patch Tuesday updates.

Devices that already have previous cumulative updates installed will only need to download the new components.

Most Windows 11 users who receive automatic certificate trust list updates through Microsoft’s online service do not need these out-of-band releases.

In other news, Microsoft has expanded Windows 11 26H2 to all eligible PCs. The company has also confirmed two Universal Print bugs affecting Windows 11 and Konica Minolta devices and warned that Windows Server 2016 support will end soon.

Via Neowin