Improper Authentication in FreeRDP - #VU139936
Published: July 28, 2026
Vulnerability identifier: #VU139936
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-287
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass authentication.
The vulnerability exists due to improper authentication in the RDSTLS server authentication state machine in libfreerdp/core/rdstls.c when processing a credential-less Capabilities PDU at the authentication step. A remote attacker can send a credential-less Capabilities PDU instead of an Authentication Request to bypass authentication.
Only deployments with RDSTLS enabled are vulnerable.
Affected software
FreeRDP
Remediation
Install security update from vendor's website.
FreeRDP - update to 3.28.0