KB5091571: Domain controllers (known issue)] Fixed

April 19, 2026—KB5091571 (OS Build 25398.2276) Out-of-band

Summary
This out-of-band update for Windows Server, version 23H2 (KB5091571) is cumulative. It includes fixes and improvements that are part of the following update:

• April 14, 2026—KB5082060 (OS Build 25398.2274)

The following is a summary of the issues that this out-of-band update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting.

- [Domain controllers (known issue)] Fixed: After installing the April 14, 2026, (KB5082060) Windows security update and restarting, domain controllers with multi-domain forests that use Privileged Access Management (PAM), might experience startup issues. In some cases, Local Security Authority Subsystem Service (LSASS) might stop responding, leading to repeated restarts, and preventing authentication and directory services, which can make the domain unavailable.

If you installed earlier updates, your device downloads and installs only the new updates contained in this package.