{"cve":"CVE-2021-26813","nvd":{"published":"2021-03-03T16:15:13.197","modified":"2026-06-17T03:43:49.013","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1333"],"references":["https://github.com/trentm/python-markdown2/pull/387","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"],"products":["fedoraproject:fedora","markdown2_project:markdown2"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-26813","score":0.02319,"percentile":0.83456,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-jr9p-r423-9m2r","url":"https://osv.dev/vulnerability/GHSA-jr9p-r423-9m2r","summary":"markdown2 Regular Expression Denial of Service ","modified":"2025-02-21T05:30:49.729149Z","packages":[{"ecosystem":"PyPI","name":"markdown2","purl":"pkg:pypi/markdown2","ranges":[">=1.0.1.18 <2.4.0"],"fixed":["2.4.0"]}]},{"id":"PYSEC-2021-20","url":"https://osv.dev/vulnerability/PYSEC-2021-20","summary":"","modified":"2023-11-08T04:05:22.342158Z","packages":[{"ecosystem":"PyPI","name":"markdown2","purl":"pkg:pypi/markdown2","ranges":[">=1.0.1.18 <2.4.0"],"fixed":["2.4.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}