Bug 2510026 (CVE-2026-66402) - CVE-2026-66402 FreeRDP: FreeRDP: Server Identity Verification Bypass via TLS Certificate Validation Weaknesses
Summary: CVE-2026-66402 FreeRDP: FreeRDP: Server Identity Verification Bypass via TLS ...
Keywords:
Status: NEW
Alias: CVE-2026-66402
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2510318 2510319
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-01 13:04 UTC by OSIDB Bzimport
Modified: 2026-08-03 07:57 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-01 13:04:00 UTC
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.


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