Windows Server updates cause Remote Desktop Services failures

Microsoft's September cumulative updates for Windows Server are causing widespread failures in Remote Desktop Services (RDS). Administrators report that after installing the patches on Windows Server versions 2016, 2019, 2022, and 2025, systems initially function normally for several hours before connections begin to fail.

Once the issue manifests, existing RDP sessions often cannot be closed or logged out properly, and new connection attempts hang until they error out. In some instances, the problem is severe enough to render the Task Manager unusable, necessitating a hard reset of the machine to restore service. One technical investigation suggested a deadlock between the RDP stack and the Local Session Manager during session teardown.

The September patch was intended to address four security vulnerabilities, including a critical 'use-after-free' flaw (CVE-2026-69525) rated 9.8 out of 10 by Microsoft. Currently, the most reliable workaround for administrators is to uninstall the cumulative update.