Improper Certificate Validation in FreeRDP - #VU156169
Published: October 19, 2026
Vulnerability identifier: #VU156169
CSH Severity: Medium
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass server-identity verification and intercept or modify RDP session contents.
The vulnerability exists due to improper certificate validation in FreeRDP's tls_verify_certificate() when checking a certificate's Common Name despite the presence of non-matching DNS Subject Alternative Names. A remote attacker can intercept or redirect an RDP connection and present a certificate that chains to a client-trusted CA, with a Common Name matching the target hostname but only non-matching DNS Subject Alternative Names, to bypass server-identity verification and read or manipulate session contents without a certificate warning.
Affected software
FreeRDP
Remediation
Install security update from vendor's website.
FreeRDP - update to 3.32.2