Improper Certificate Validation Affecting freerdp3 package, versions <3.30.0+dfsg-0ubuntu0.24.04.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.29% (21st percentile)

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  • Snyk IDSNYK-UBUNTU2404-FREERDP3-18519757
  • published18 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 Ubuntu:24.04 freerdp3 to version 3.30.0+dfsg-0ubuntu0.24.04.1 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 Ubuntu. See How to fix? for Ubuntu:24.04 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