{
   "document": {
      "aggregate_severity": {
         "text": "critical"
      },
      "category": "csaf_security_advisory",
      "csaf_version": "2.0",
      "distribution": {
         "tlp": {
            "label": "WHITE",
            "url": "https://www.first.org/tlp/"
         }
      },
      "lang": "en",
      "notes": [
         {
            "category": "description",
            "text": "Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret.\n\nThe session keyword freezes its options onto the application as given: it does not require a secret, warn, or refuse to start when one is absent. The cookie read and the write-back both default that key to the empty string, so a declaration with no secret option, or with an undefined or empty one, signs and verifies with a zero-length HMAC-SHA256 key.\n\nAn attacker who knows the cookie format can then mint one offline carrying any contents the session holds, such as a user identifier or a role. Nothing marks the misconfiguration at runtime: cookies are well formed and sessions round-trip as expected.",
            "title": "Vulnerability Description"
         }
      ],
      "publisher": {
         "category": "other",
         "contact_details": "gdt@cpan.org",
         "name": "giterlizzi",
         "namespace": "https://github.com/giterlizzi/"
      },
      "references": [
         {
            "category": "self",
            "summary": "CPANSA-Punk-2026-75870 JSON",
            "url": "https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-punk-2026-75870.json"
         },
         {
            "category": "external",
            "summary": "https://metacpan.org/release/LNATION/Punk-0.17/source/include/punk/punk_session.h",
            "url": "https://metacpan.org/release/LNATION/Punk-0.17/source/include/punk/punk_session.h"
         },
         {
            "category": "external",
            "summary": "https://metacpan.org/release/LNATION/Punk-0.17/view/lib/Punk.pm",
            "url": "https://metacpan.org/release/LNATION/Punk-0.17/view/lib/Punk.pm"
         },
         {
            "category": "external",
            "summary": "https://metacpan.org/release/LNATION/Punk-0.18/source/Changes",
            "url": "https://metacpan.org/release/LNATION/Punk-0.18/source/Changes"
         },
         {
            "category": "external",
            "summary": "http://www.openwall.com/lists/oss-security/2026/08/22/5",
            "url": "http://www.openwall.com/lists/oss-security/2026/08/22/5"
         },
         {
            "category": "external",
            "summary": "CVE-2026-75870 (NVD)",
            "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75870"
         }
      ],
      "title": "Punk vulnerability",
      "tracking": {
         "current_release_date": "2026-08-22T00:00:00",
         "generator": {
            "engine": {
               "name": "CSAF Perl Toolkit",
               "version": "0.26"
            }
         },
         "id": "CPANSA-Punk-2026-75870",
         "initial_release_date": "2026-08-22T00:00:00",
         "revision_history": [
            {
               "date": "2026-08-22T00:00:00",
               "number": "1",
               "summary": "First release"
            }
         ],
         "status": "final",
         "version": "1"
      }
   },
   "product_tree": {
      "branches": [
         {
            "branches": [
               {
                  "category": "product_version_range",
                  "name": "vers:cpan/<0.18",
                  "product": {
                     "name": "Punk less than 0.18",
                     "product_id": "CSAFPID-0001",
                     "product_identification_helper": {
                        "purl": "pkg:cpan/Punk"
                     }
                  }
               },
               {
                  "category": "product_version_range",
                  "name": "vers:cpan/>=0.18",
                  "product": {
                     "name": "Punk greater than or equal 0.18",
                     "product_id": "CSAFPID-0002",
                     "product_identification_helper": {
                        "purl": "pkg:cpan/Punk"
                     }
                  }
               }
            ],
            "category": "product_name",
            "name": "Punk"
         }
      ]
   },
   "vulnerabilities": [
      {
         "cve": "CVE-2026-75870",
         "cwe": {
            "id": "CWE-1394",
            "name": "Use of Default Cryptographic Key"
         },
         "notes": [
            {
               "category": "description",
               "text": "Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret.\n\nThe session keyword freezes its options onto the application as given: it does not require a secret, warn, or refuse to start when one is absent. The cookie read and the write-back both default that key to the empty string, so a declaration with no secret option, or with an undefined or empty one, signs and verifies with a zero-length HMAC-SHA256 key.\n\nAn attacker who knows the cookie format can then mint one offline carrying any contents the session holds, such as a user identifier or a role. Nothing marks the misconfiguration at runtime: cookies are well formed and sessions round-trip as expected.",
               "title": "Vulnerability Description"
            }
         ],
         "product_status": {
            "fixed": [
               "CSAFPID-0002"
            ],
            "known_affected": [
               "CSAFPID-0001"
            ]
         },
         "scores": [
            {
               "cvss_v3": {
                  "baseScore": 9.1,
                  "baseSeverity": "CRITICAL",
                  "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
                  "version": "3.1"
               },
               "products": [
                  "CSAFPID-0001"
               ]
            }
         ]
      }
   ]
}