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FreeRDP before 3.29.0 (affected versions <= 3.28.0) contains multiple TLS certificate identity validation weaknesses in tls_verify_certificate(),… (CVE-2026-66402)

0
Critical
Published: 08/01/2026 (08/01/2026, 15:30:25 UTC)
Source: GCVE Database

Description

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 v3.1

Score 9.8critical

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Technical Details

Gcve Source
db.gcve.eu
Osv Id
GHSA-759r-h698-g7xj
Osv Schema Version
1.4.0
Aliases
["CVE-2026-66402"]
Ecosystems
[]
Database Specific Severity
CRITICAL
Cvss Version
3.1

Threat ID: 6a6e6299bf32cb7a344f9ed5

Added to database: 08/01/2026, 21:18:17 UTC

Last updated: 08/01/2026, 21:18:17 UTC

Views: 1

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