FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass

{
  "id": "15fd270e1f50cbeb69543f589f1568f9d5dfac75b1c0ed3a79e40366b5294a9d",
  "url": "https://osv.dev/vulnerability/CVE-2026-91949",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass",
    "summary": "FreeRDP server versions before 3.31.0 contain a protocol negotiation bypass vulnerability that allows unauthenticated attackers to establish RDSTLS connections despite server policy disabling them. Attackers can send incompatible protocol requests, receive negotiation failures, then complete TLS handshake and enter RDSTLS to bypass pre-authentication transport restrictions.",
    "evidence": "osv:CVE-2026-91949",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-91949",
      "aliases": [
        "CVE-2026-91949",
        "GHSA-x7v6-xfx3-52j6"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/freerdp/freerdp",
              "type": "GIT",
              "events": [
                {
                  "introduced": "a34fa7c49d2a39aa49ace1d7bea9656912d8c7cb"
                },
                {
                  "fixed": "aa8650b300aa4cabd85d9c72b431301509b9043f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "3.31.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "cpe": "cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "3.31.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.5.1",
            "3.5.0",
            "3.4.0",
            "3.3.0",
            "3.2.0",
            "3.1.0",
            "3.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-91949.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:22.241332789Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91949.json",
        "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-x7v6-xfx3-52j6",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-91949",
        "https://www.vulncheck.com/advisories/freerdp-3.0.0-through-3.30.0-protocol-negotiation-bypass"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-693"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91949.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-91949",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 488710,
  "published_at": "2026-09-15T15:18:07.144+00:00"
}