{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "3.29.0"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "743f437f434c6814d3ba265c75cab14673bc2911"
            }
          ],
          "repo": "https://github.com/freerdp/freerdp",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-43hh-p3vw-hfx3"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-295"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66402.json"
  },
  "details": "FreeRDP before 3.29.0 (affected versions \u003c= 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.",
  "id": "CVE-2026-66402",
  "modified": "2026-08-04T11:31:12.170537813Z",
  "published": "2026-08-01T12:22:17.331Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66402.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-43hh-p3vw-hfx3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-66402"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/freerdp-before-tls-certificate-identity-validation-bypass"
    },
    {
      "type": "FIX",
      "url": "https://github.com/FreeRDP/FreeRDP/commit/b9533f07f98c25ed01c5f543b4d0ce73e120f5fd"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass"
}