Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-66402

CVE-2026-66402CRITICAL

FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass

  AV  AC  AT  PR  UI  VC  VI  VA   CVSS    EPSS   %ile   KEV
   N   L   N   N   N   H   H   H    9.3   .0050   40.9     —

AFFECTED
  Product  Versions     Fixed
  FreeRDP  unspecified  3.29.0

TIMELINE
  Jul 26  Reserved by VulnCheck
  Aug 1   Published (CNA: VulnCheck)
  Oct 2   EXPLOIT PUBLISHED — CVE-2026-66402 (FreeRDP). Public exploit reference added.

CWE-295 · CNA: VulnCheck · CVSS v4.0 · 3 references · NVD status: Analyzed

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
July 26, 2026	Reserved	Reserved by VulnCheck
August 1, 2026	Published	Published (CNA: VulnCheck)
October 2, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-66402 (FreeRDP). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
FreeRDP	FreeRDP	—	—	3.29.0

Weaknesses

CWE-295

References (3)

https://github.com/FreeRDP/FreeRDP/commit/b9533f07f98c25ed01c5f543b4d0ce73e120f5fd [Patch]
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-43hh-p3vw-hfx3 [Vendor Advisory, Exploit, Mitigation]
https://www.vulncheck.com/advisories/freerdp-before-tls-certificate-identity-validation-bypass [Patch, Third Party Advisory]

Authoritative record: CVE-2026-66402 at cve.org

Vendors: freerdp

Weaknesses: CWE-295

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-66402 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.