{
   "document": {
      "aggregate_severity": {
         "text": "medium"
      },
      "category": "csaf_security_advisory",
      "csaf_version": "2.0",
      "distribution": {
         "tlp": {
            "label": "WHITE",
            "url": "https://www.first.org/tlp/"
         }
      },
      "lang": "en",
      "notes": [
         {
            "category": "description",
            "text": "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep.\n\nnameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label.\n\nAny caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.",
            "title": "Vulnerability Description"
         }
      ],
      "publisher": {
         "category": "other",
         "contact_details": "gdt@cpan.org",
         "name": "giterlizzi",
         "namespace": "https://github.com/giterlizzi/"
      },
      "references": [
         {
            "category": "self",
            "summary": "CPANSA--2026-19953 JSON",
            "url": "https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa--2026-19953.json"
         },
         {
            "category": "external",
            "summary": "https://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patch",
            "url": "https://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patch"
         },
         {
            "category": "external",
            "summary": "https://github.com/libwww-perl/URI/pull/191",
            "url": "https://github.com/libwww-perl/URI/pull/191"
         },
         {
            "category": "external",
            "summary": "https://metacpan.org/release/OALDERS/URI-5.36/changes",
            "url": "https://metacpan.org/release/OALDERS/URI-5.36/changes"
         },
         {
            "category": "external",
            "summary": "https://www.rfc-editor.org/rfc/rfc5891#section-5.2",
            "url": "https://www.rfc-editor.org/rfc/rfc5891#section-5.2"
         },
         {
            "category": "external",
            "summary": "http://www.openwall.com/lists/oss-security/2026/08/31/14",
            "url": "http://www.openwall.com/lists/oss-security/2026/08/31/14"
         },
         {
            "category": "external",
            "summary": "CVE-2026-19953 (NVD)",
            "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19953"
         }
      ],
      "title": "URI vulnerability",
      "tracking": {
         "current_release_date": "2026-08-31T00:00:00",
         "generator": {
            "engine": {
               "name": "CSAF Perl Toolkit",
               "version": "0.26"
            }
         },
         "id": "CPANSA--2026-19953",
         "initial_release_date": "2026-08-31T00:00:00",
         "revision_history": [
            {
               "date": "2026-08-31T00:00:00",
               "number": "1",
               "summary": "First release"
            }
         ],
         "status": "final",
         "version": "1"
      }
   },
   "product_tree": {
      "branches": [
         {
            "branches": [
               {
                  "category": "product_version_range",
                  "name": "vers:cpan/<5.36",
                  "product": {
                     "name": "URI less than 5.36",
                     "product_id": "CSAFPID-0001",
                     "product_identification_helper": {
                        "purl": "pkg:cpan/URI"
                     }
                  }
               },
               {
                  "category": "product_version_range",
                  "name": "vers:cpan/>=5.36",
                  "product": {
                     "name": "URI greater than or equal 5.36",
                     "product_id": "CSAFPID-0002",
                     "product_identification_helper": {
                        "purl": "pkg:cpan/URI"
                     }
                  }
               }
            ],
            "category": "product_name",
            "name": "URI"
         }
      ]
   },
   "vulnerabilities": [
      {
         "cve": "CVE-2026-19953",
         "cwe": {
            "id": "CWE-1289",
            "name": "Improper Validation of Unsafe Equivalence in Input"
         },
         "notes": [
            {
               "category": "description",
               "text": "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep.\n\nnameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label.\n\nAny caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.",
               "title": "Vulnerability Description"
            }
         ],
         "product_status": {
            "fixed": [
               "CSAFPID-0002"
            ],
            "known_affected": [
               "CSAFPID-0001"
            ]
         },
         "scores": [
            {
               "cvss_v3": {
                  "baseScore": 6.5,
                  "baseSeverity": "MEDIUM",
                  "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
                  "version": "3.1"
               },
               "products": [
                  "CSAFPID-0001"
               ]
            }
         ]
      }
   ]
}