symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence

{
  "id": "fed91ad0f7d2909cc2a7a6abed0bee093025dcab30889bc702f564aede543e7a",
  "url": "https://osv.dev/vulnerability/CVE-2026-46644",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence",
    "summary": "Symfony Polyfill backports PHP features and provides compatibility layers for extensions and functions. From 1.17.1 until 1.38.1, symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload is empty or decodes to ASCII-only code points because Idn::process() does not enforce the UTS #46 revision 33 requirement that decoded ACE labels contain at least one non-ASCII code point. Originally unequal domain names can be regarded as equal, which can lead to blacklist bypassing, inconsistent URL parsing, and server-side request forgery in applications using the polyfill to canonicalise or compare hostnames. This issue is fixed in version 1.38.1.",
    "evidence": "osv:CVE-2026-46644",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-46644",
      "aliases": [
        "CVE-2026-46644",
        "GHSA-2xf4-cg6j-vhgq"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/symfony/polyfill",
              "type": "GIT",
              "events": [
                {
                  "introduced": "c36c1b42c49a5519b5424733de58412d6f387209"
                },
                {
                  "fixed": "09e53d15109121636a416310ea0d510bd292c463"
                },
                {
                  "fixed": "1be936e2491ccebe152bd736dfc91eb1422c8bec"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.17.1"
                      },
                      {
                        "fixed": "1.38.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "1be936e2491ccebe152bd736dfc91eb1422c8bec"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "09e53d15109121636a416310ea0d510bd292c463"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.38.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.38.0",
            "v1.37.0",
            "v1.36.0",
            "v1.35.0",
            "v1.34.0",
            "v1.33.0",
            "v1.32.0",
            "v1.31.0",
            "v1.30.0",
            "v1.29.0",
            "v1.28.0",
            "v1.27.0",
            "v1.26.0",
            "v1.25.0",
            "v1.24.0",
            "v1.23.1",
            "v1.23.0",
            "v1.22.1",
            "v1.22.0",
            "v1.20.0",
            "v1.19.0",
            "v1.18.1",
            "v1.18.0",
            "v1.17.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46644.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.832843667Z",
      "provider": "osv",
      "references": [
        "https://github.com/symfony/polyfill/releases/tag/v1.38.1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46644.json",
        "https://github.com/symfony/polyfill/security/advisories/GHSA-2xf4-cg6j-vhgq",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46644",
        "https://github.com/symfony/polyfill/commit/1be936e2491ccebe152bd736dfc91eb1422c8bec"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1289"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46644.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46644",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 500022,
  "published_at": "2026-07-14T20:48:31.771+00:00"
}