CVE-2019-25781
HIGH
NVD
CVSS Score
7.5
Severity
HIGH
Published
Oct 29, 2026
Vendor
unknown
Description
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 [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.
References
- https://github.com/Python-Markdown/markdown
- https://github.com/Python-Markdown/markdown/blob/b41e0aaf1181f1a8cb200cf5a815aad7c0020d23/markdown/inlinepatterns.py#L1155-L1172
- https://github.com/Python-Markdown/markdown/issues/1654
- https://github.com/Python-Markdown/markdown/issues/798
- https://www.vulncheck.com/advisories/python-markdown-3.0-through-3.11.2-denial-of-service-via-link-bracket-parsing