{"id":"CVE-2019-25781","title":"Python-Markdown 3.0 through 3.11.2 Denial of Service via Link Bracket Parsing","summary":"Python-Markdown 3.0 through 3.11.2 contains an algorithmic complexity vulnerability in inline link parsing that allows remote attackers to exhaust CPU through unmatched brackets. Attackers can submit short Markdown containing repeated [ …","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-407"],"vendor":"Python-Markdown","product":"Markdown","affected":["Markdown >= 3.0 <= 3.11.2"],"published":"2026-10-29","updated":"2026-10-29","sourceUpdated":"2026-10-29T13:08:49.597Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2019-25781","references":[{"url":"https://github.com/Python-Markdown/markdown/issues/798","label":"GitHub Issue #798"},{"url":"https://github.com/Python-Markdown/markdown"},{"url":"https://github.com/Python-Markdown/markdown/issues/1654","label":"GitHub Issue #1654"},{"url":"https://github.com/Python-Markdown/markdown/blob/b41e0aaf1181f1a8cb200cf5a815aad7c0020d23/markdown/inlinepatterns.py#L1155-L1172"},{"url":"https://www.vulncheck.com/advisories/python-markdown-3.0-through-3.11.2-denial-of-service-via-link-bracket-parsing","label":"VulnCheck Advisory: Python-Markdown 3.0 through 3.11.2 Denial of Service via Link Bracket Parsing"}],"tags":["cve.org"],"epss":0.00422,"epssPercentile":0.36552,"ingestedAt":"2026-11-01T18:59:04.480Z","slug":"CVE-2019-25781","body":"## Overview\n\nPython-Markdown 3.0 through 3.11.2 contains an algorithmic complexity vulnerability in inline link parsing that allows remote attackers to exhaust CPU through unmatched brackets. Attackers can submit short Markdown containing repeated [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.\n\n## Affected\n\n- `Markdown >= 3.0 <= 3.11.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}