picklescan - Arbitrary Code Execution via lib2to3.pgen2.pgen.ParserGenerator.make_label Detection Bypass

{
  "id": "8f2fde4b08612822c60f8ffeecab17dedb77acf461badf3c2a7a30ef3ea6565c",
  "url": "https://osv.dev/vulnerability/CVE-2025-71343",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "picklescan - Arbitrary Code Execution via lib2to3.pgen2.pgen.ParserGenerator.make_label Detection Bypass",
    "summary": "picklescan before 0.0.30 fails to detect malicious pickle files that exploit lib2to3.pgen2.pgen.ParserGenerator.make_label function in the reduce method. Attackers can craft malicious pickle files with embedded code that evades detection but executes arbitrary commands when pickle.load() is called.",
    "evidence": "osv:CVE-2025-71343",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-71343",
      "aliases": [
        "CVE-2025-71343",
        "GHSA-p9w7-82w4-7q8m"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mmaitre314/picklescan",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1931c2d04eaca8d20597705ff39cab78ba364e4b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.0.30"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.0.30"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.0.29",
            "v0.0.28",
            "v0.0.27",
            "v0.0.26",
            "v0.0.25",
            "v0.0.24",
            "v0.0.23",
            "v0.0.22",
            "v0.0.21",
            "v0.0.20",
            "v0.0.19",
            "v0.0.18",
            "v0.0.17",
            "v0.0.15",
            "v0.0.14",
            "v0.0.13",
            "v0.0.12",
            "v0.0.11",
            "v0.0.10",
            "v0.0.9",
            "v0.0.8",
            "v0.0.7",
            "v0.0.6",
            "v0.0.5",
            "v0.0.4",
            "v0.0.3",
            "v0.0.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-71343.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.854262463Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71343.json",
        "https://github.com/mmaitre314/picklescan/security/advisories/GHSA-p9w7-82w4-7q8m",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-71343",
        "https://www.vulncheck.com/advisories/picklescan-arbitrary-code-execution-via-lib2to3-pgen2-pgen-parsergenerator-make-label-detection-bypass"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-502"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71343.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-71343",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507100,
  "published_at": "2026-07-04T01:23:32.43+00:00"
}