Windows 11 RDP failures following Microsoft update KB5064081 (4380493)

Following a Windows update the RDP sessions using Safeguard fail. RDP sessions that bypass Safeguard are successful.

August 29, 2025—KB5064081 (OS Build 26100.5074) Preview August 29, 2025—KB5064081 (OS Build 26100.5074) Preview - Microsoft Support

The log related error in an SPS Support Bundle is shown as follows:

CSSP Packet contains NTSTATUS error code; error_code='80090308'

CSSP Packet; version='6', tokens='0'

CSSP errorCode; value='0x80090308'

Failed to mangle SPNEGO message; status='5', last_msg='NULL'

Failed to mangle CredSSP packet;

Error parsing incoming data;

Customers may choose to uninstall at their discretion the KB5064081 hotfix until a solution is made public.