Systems administrators across the globe are grappling with a severe operational headache after deploying Microsoft's September 2026 Patch Tuesday cumulative security updates. Widespread reports confirm that the patches introduce a critical deadlock bug in Remote Desktop Services (RDS), rendering host servers completely inaccessible to remote administration.
The disruption affects primary enterprise server releases, specifically Windows Server 2019 (KB5122876), Windows Server 2022 (KB5122882), and Windows Server 2025 (KB5122871).
Failure Anatomy: The Local Session Manager Hang
What makes the issue particularly insidious for IT operations is its delayed manifestation. Affected servers appear to boot, apply the update, and function normally for the first several hours of production activity. The breakdown occurs when active users disconnect or attempt to log out of their remote desktop sessions:
- LSM Process Lockup: The Windows Local Session Manager (
lsm.exe) process enters a deadlock condition while attempting to tear down session resources. - RDP Connection Hang: Once the deadlock triggers, any subsequent user or administrator attempting to establish an RDP connection becomes stuck indefinitely at the "Configuring remote session..." or "Securing connection..." splash screen before timing out.
- Management Tool Unresponsiveness: Remote PowerShell sessions, Task Manager remote process viewers, and administrative MMC consoles freeze when attempting to query terminal services session states.
- Hard Reset Required: Because session-handling threads cannot terminate cleanly, standard graceful shutdowns fail, forcing administrators to trigger hard chassis power-cycles or hypervisor-level virtual machine resets.
When an update designed to remediate privilege escalation bugs breaks the primary out-of-band management protocol for remote servers, operations teams are left stranded without remote access.
The Admin Dilemma: Roll Back or Stay Vulnerable?
The operational failure places enterprise security and infrastructure leaders in an acute dilemma. The September Patch Tuesday updates addressed over 900 vulnerabilities, including actively exploited elevation-of-privilege zero-days in the Windows kernel and filesystem drivers.
Uninstalling the cumulative updates immediately restores Remote Desktop Services reliability, but strips systems of crucial protections against active in-the-wild exploitation chains. For multi-tenant hosting providers, healthcare clinics running virtual desktop pools, and cloud MSPs, leaving servers running unstable updates is equally untenable.
Interim Workarounds & Guidance
While Microsoft works on an emergency Out-of-Band (OOB) quality update, administrators can take the following triage measures:
- Halt Rollout to Remaining Fleet: Immediately pause automatic update deployment rings for Windows Server infrastructure, particularly dedicated RDS Session Hosts and jump boxes.
- Disable Remote Audio Redirection: Multiple community enterprise administrators report that disabling client audio playback redirection via Group Policy reduces the occurrence of LSM session deadlocks:
Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Device and Resource Redirection > Do not allow audio and video playback redirection = Enabled - Deploy Out-of-Band Management Alternatives: Ensure non-RDP administration channels, such as hardware iLO/iDRAC consoles, serial-over-LAN, or SSH daemon services (OpenSSH for Windows), are enabled and validated before applying updates.
- Monitor Windows Release Health: Track the official Windows Release Health portal for Microsoft's mitigation scripts and superseding hotfix rollouts.
