Security advisory

{
  "id": "9fa5fae2131166f1c6fb4c822ff0c09b9818418bc24ab07e22ba6f39dcb671e4",
  "url": "https://osv.dev/vulnerability/CVE-2019-20477",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2019-20477",
    "summary": "PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.",
    "evidence": "osv:CVE-2019-20477",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2019-20477",
      "aliases": [
        "CVE-2019-20477",
        "GHSA-3pqx-4fqf-j49f",
        "PYSEC-2020-176"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/yaml/pyyaml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e471e86bf6dabdad45a1438c20a4a5c033eb9034"
                },
                {
                  "last_affected": "a9b98a3daa43d43afd8051b014d5b4154d141913"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:pyyaml:pyyaml:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.1"
                      },
                      {
                        "last_affected": "5.1.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2019-20477.json"
          }
        }
      ],
      "modified": "2026-10-20T10:52:40.819423529Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/",
        "https://github.com/yaml/pyyaml/blob/master/CHANGES",
        "https://www.exploit-db.com/download/47655"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "30"
                  },
                  {
                    "last_affected": "30"
                  },
                  {
                    "introduced": "31"
                  },
                  {
                    "last_affected": "31"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2019-20477",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 383733,
  "published_at": "2020-02-19T04:15:10.803+00:00"
}