Webhook SSRF guard bypassed by IPv6 transition addresses (NAT64/6to4/Teredo pass is_global check) in vulnerability-lookup

{
  "id": "16286e1a135161bc02d7df4b07bc6fcf36ef8e7e13081e40d99f4e73c5ffc9a5",
  "url": "https://osv.dev/vulnerability/CVE-2026-72761",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Webhook SSRF guard bypassed by IPv6 transition addresses (NAT64/6to4/Teredo pass is_global check) in vulnerability-lookup",
    "summary": "The webhook URL validator in `website/notifications/webhooks.py` uses `ip.is_global` to reject non-public addresses after DNS resolution. IPv6 transition addresses (NAT64 `64:ff9b::/96`, 6to4 `2002::/16`, Teredo `2001:0000::/32`) are classified as globally routable by IANA, so `is_global` returns `True` even when the embedded IPv4 targets a private, loopback, or cloud metadata destination. An attacker can register a webhook pointing at a hostname that resolves to a transition address to bypass the SSRF guard and exfiltrate vulnerability data to an internal endpoint. The vulnerability was introduced on a non-release version. The fix was already done on HEAD. It only affects organisation running the HEAD.",
    "evidence": "osv:CVE-2026-72761",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-72761",
      "aliases": [
        "CVE-2026-72761"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/vulnerability-lookup/vulnerability-lookup",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "f3e0c6899c5b3823dcfd860fc6cb3edbedc9bf65"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "fixed": "f3e0c6899c5b3823dcfd860fc6cb3edbedc9bf65"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.5.0",
            "v5.4.0",
            "v5.3.0",
            "v5.2.0",
            "v5.1.0",
            "v5.0.0",
            "v4.6.0",
            "v4.5.0",
            "v4.4.0",
            "v4.3.0",
            "v4.2.0",
            "v4.1.0",
            "v4.0.0",
            "v3.0.1",
            "v3.0.0",
            "v2.21.0",
            "v2.20.0",
            "v2.19.0",
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            "v2.17.0",
            "v2.16.1",
            "v2.16.0",
            "v2.15.0",
            "v2.13.0",
            "v2.12.0",
            "v2.10.1",
            "v2.10.0",
            "v2.9.0",
            "v2.7.1",
            "v2.7.0",
            "v2.6.0",
            "v2.5.0",
            "v2.4.0",
            "v2.3.0",
            "v2.2.0",
            "v2.1.0",
            "v1.7.0",
            "v1.6.0",
            "v1.5.0",
            "v1.4.0",
            "v1.3.0",
            "v1.2.0",
            "v1.1.0",
            "v1.0.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72761.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.776585102Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72761.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-72761",
        "https://github.com/vulnerability-lookup/vulnerability-lookup/commit/f3e0c6899c5b3823dcfd860fc6cb3edbedc9bf65",
        "https://github.com/vulnerability-lookup/vulnerability-lookup"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-918"
        ],
        "cna_assigner": "CIRCL",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72761.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-72761",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498457,
  "published_at": "2026-08-10T14:33:13.106+00:00"
}