Improper Certificate Validation Affecting freerdp3 package, versions <3.29.0+dfsg-1


Severity

Recommended
0.0
critical
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.29% (22nd percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-DEBIAN14-FREERDP3-18505506
  • published2 Aug 2026
  • disclosed1 Aug 2026

Introduced: 1 Aug 2026

NewCVE-2026-66402  (opens in a new tab)
CWE-295  (opens in a new tab)

How to fix?

Upgrade Debian:14 freerdp3 to version 3.29.0+dfsg-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream freerdp3 package and not the freerdp3 package as distributed by Debian. See How to fix? for Debian:14 relevant fixed versions and status.

FreeRDP before 3.29.0 (affected versions <= 3.28.0) contains multiple TLS certificate identity validation weaknesses in tls_verify_certificate(), tls_match_hostname(), and x509_utils_get_dns_names(). Because FreeRDP performs custom Common Name and DNS SAN string matching instead of using OpenSSL's length-aware identity validation APIs, it (1) truncates DNS SAN values at embedded NUL bytes (accepting e.g. 'victim.example\0.attacker.example' as 'victim.example'), (2) accepts a matching Common Name even when non-matching DNS SAN entries are present, and (3) accepts IP-literal targets via DNS/CN matching without comparing iPAddress SANs. Under a trusted or misissued certificate chain, an attacker positioned to present such a certificate can bypass server identity verification, weakening TLS server authentication.

CVSS Base Scores

version 3.1