From bleepingcomputer.com
Microsoft is investigating LSASS memory leaks (caused by Windows Server updates released during the November Patch Tuesday) that might lead to freezes and restarts on some domain controllers.
LSASS (short for Local Security Authority Subsystem Service) is responsible for enforcing security policies on Windows systems, and it handles access token creation, password changes, and user logins.
If this service crashes, logged-in users immediately lose access to Windows accounts on the machine, and they’re shown a system restart error followed by a system reboot.