Flyto2 Core: SSRF guard bypass via IPv6 transition addresses (IPv4-mapped / 6to4 / NAT64) in validate_url_ssrf

{
  "id": "b943bd3f08bb3cdaba7dd173cb30a9a715bc05eceb0deb0f26708bade651cf4c",
  "url": "https://osv.dev/vulnerability/CVE-2026-55787",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Flyto2 Core: SSRF guard bypass via IPv6 transition addresses (IPv4-mapped / 6to4 / NAT64) in validate_url_ssrf",
    "summary": "Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.3, validate_url_ssrf and is_private_ip in src/core/utils.py compare resolved addresses only against native private IPv4 and IPv6 ranges and do not unwrap IPv4-mapped, IPv4-compatible, 6to4, or NAT64 transition addresses. An authenticated workflow author can provide a transition-form literal URL through the Execution API POST /v1/execute route, http.get, or sibling guarded outbound-request modules, causing the guard to accept an address whose embedded IPv4 points to loopback, RFC 1918, or cloud metadata services. On a host that routes the selected transition form, the outbound request reaches the internal destination and returns the response body to the workflow caller, enabling read SSRF and disclosure of internal-service data or cloud credentials. This issue is fixed in version 2.26.3.",
    "evidence": "osv:CVE-2026-55787",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-55787",
      "aliases": [
        "CVE-2026-55787",
        "GHSA-794r-5rp2-fpg8",
        "PYSEC-2026-2481"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/flytohub/flyto-core",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e8c6fd9902ff93389cd2e3ecaa472b7d91aec67e"
                },
                {
                  "fixed": "519e040384a74984848c4e84a6600e5f1020a6d2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.26.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "519e040384a74984848c4e84a6600e5f1020a6d2"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e8c6fd9902ff93389cd2e3ecaa472b7d91aec67e"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.26.3"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.26.0",
            "v2.25.27",
            "v2.17.6",
            "v2.16.3",
            "v2.5.0",
            "v2.2.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55787.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.064657120Z",
      "provider": "osv",
      "references": [
        "https://github.com/flytohub/flyto-core/releases/tag/v2.26.3",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55787.json",
        "https://github.com/flytohub/flyto-core/security/advisories/GHSA-794r-5rp2-fpg8",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-55787",
        "https://github.com/flytohub/flyto-core/commit/519e040384a74984848c4e84a6600e5f1020a6d2",
        "https://github.com/flytohub/flyto-core/pull/20"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-918"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55787.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-55787",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518588,
  "published_at": "2026-10-14T18:13:52.454+00:00"
}