RDP Login Failures After Windows 11 24H2 Update KB5065426
- Steven Paniccia
- Jun 5
- 1 min read
After installing Microsoft’s cumulative security update KB5065426 for Windows 11 (version 24H2, September 2025), many organizations are encountering RDP login failures when administrators or end users attempt to access virtual desktops.
Root Cause:
Microsoft has confirmed that the issue arises when multiple systems share identical machine identities. This can occur in the following scenarios:
Duplicate MachineGUID values
Duplicate SID values
VDI images cloned without proper resealing
These identity conflicts disrupt NTLM authentication, causing login failures even when correct credentials are entered.
Who Is Affected:
Admins or users RDPing between two systems that both have KB5065426 installed and share the same SID or MachineGUID → RDP authentication fails.
Who is NOT Affected:
Admins or users RDPing from machines without KB5065426 installed
End users accessing desktops through normal login methods
The Fix
Microsoft released a Known Issue Rollback (KIR) MSI package along with a Group Policy update. These must be applied to restore RDP functionality.
1. Install the Microsoft KIR Hotfix on the target desktop (direct link below)
2. Apply the Required Group Policy Setting:
Computer Configuration → Administrative Templates → All SettingsSet: KB5065426 250912_02251 Known Issue Rollback → Disabled
3. Reboot the Desktop: A restart is required. The MSI alone will not resolve the issue without the GPO applied.
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