Security advisory

{
  "id": "5d6032cbb4a6ecef6b3c439e2e40441f009833795c79c1d6c5b033a938233e3b",
  "url": "https://osv.dev/vulnerability/CVE-2021-26813",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-26813",
    "summary": "markdown2 >=1.0.1.18, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. If an attacker provides a malicious string, it can make markdown2 processing difficult or delayed for an extended period of time.",
    "evidence": "osv:CVE-2021-26813",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-26813",
      "aliases": [
        "CVE-2021-26813",
        "GHSA-jr9p-r423-9m2r",
        "PYSEC-2021-20"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/trentm/python-markdown2",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6d11f0f1ef9e112faeaf8028f631d2f825f991a6"
                },
                {
                  "fixed": "31491857f247f553c4006b7ef55823deefb9e8e9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:markdown2_project:markdown2:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.0.1.18"
                      },
                      {
                        "fixed": "2.4.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2.3.10",
            "2.3.9",
            "2.3.8",
            "2.3.7",
            "2.3.6",
            "2.3.5",
            "2.3.4",
            "2.3.3",
            "2.3.2",
            "2.3.1",
            "2.3.0",
            "2.2.3",
            "2.2.2",
            "2.2.1",
            "2.2.0",
            "2.1.0",
            "2.0.1",
            "2.0.0",
            "1.4.2",
            "1.4.1",
            "1.4.0",
            "1.3.1",
            "1.3.0",
            "1.2.0",
            "1.1.1",
            "1.1.0",
            "1.0.1.19",
            "1.0.1.18"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-26813.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:34.501695461Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BRP5RN35JZTSJ3JT4722F447ZDK7LZS5/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J752422YELXLMLZJPVJVKD2KKHHQRVEH/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JTIX5UXRDJZJ57DO4V33ZNJTNKWGBQLY/",
        "https://github.com/trentm/python-markdown2/pull/387"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "32"
                  },
                  {
                    "last_affected": "32"
                  },
                  {
                    "introduced": "33"
                  },
                  {
                    "last_affected": "33"
                  },
                  {
                    "introduced": "34"
                  },
                  {
                    "last_affected": "34"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-26813",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385624,
  "published_at": "2021-03-03T16:15:13.197+00:00"
}