Microsoft has confirmed that its September 2026 Windows security updates can destabilize Remote Desktop Services (RDS), potentially disrupting remote administration across a broad range of enterprise endpoints and servers.
Last week, Windows administrators worldwide experienced this serious bug in Remote Desktop Services (RDS), and they point out that the issue appeared right after Microsoft released its September 2026 Patch Tuesday updates.
The issue is tied to KB5124008 on Windows 11 versions 24H2 and 25H2, including OS Build 26100.9445, and equivalent September updates for other affected Windows releases.
According to Microsoft’s Windows release health dashboard, affected RDS environments may operate normally at first, then Remote Desktop Protocol (RDP) connections may begin failing after several minutes. Users can encounter sign-in failures, while servers may remain stuck indefinitely at the “Please wait for the Remote Desktop Configuration” screen, effectively preventing administrators and employees from reaching remote systems.
Remote Desktop Services Might Stop Working
The impact can extend beyond the RDP connection itself. Microsoft warned that Microsoft Management Console (MMC), RDS Licensing Diagnoser, and File Explorer may stop responding on affected machines. The Windows Update settings page can also freeze while continuously displaying a loading indicator, complicating diagnosis and routine system administration.
Microsoft marked the issue as “Mitigated” on September 11, three days after the September 8 Patch Tuesday release. The company has not disclosed a root cause, and the available documentation does not indicate that the behavior results from exploitation or a newly disclosed vulnerability. Instead, it is being tracked as a reliability regression introduced by the security update.
The affected client list spans Windows 11 versions 26H1, 25H2, 24H2, and 23H2; Windows 10 versions 22H2 and 21H2; and Windows 10 Enterprise LTSC 2019 and 2016. Affected server editions include Windows Server 2025, 2022, 2019, 2016, 2012 R2, and 2012, giving the issue potential reach across both current and legacy enterprise infrastructure.
For virtual machines that become inaccessible through RDP, Microsoft says administrators may temporarily restore connectivity by stopping, or deallocating, the affected VM and then restarting it. This is a recovery measure, not a permanent fix, so IT teams should expect the instability to return until Microsoft delivers a complete resolution.
Administrators requiring an immediate workaround can contact Microsoft Support for Business. Organizations should test September updates against RDS session hosts, licensing systems, jump servers, and remote-management workflows before wider deployment, while ensuring they retain an alternate management path such as a cloud console or hypervisor interface.
Microsoft is developing a permanent fix for a future Windows update but has not announced a release date. Because uninstalling a security update would also remove its protections, administrators should avoid broad rollback decisions without assessing exposure, operational impact, and Microsoft’s available mitigation for their environment.
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