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 [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.

Remediation

1. Inventory every Python-Markdown Markdown deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Advisoryhttps://www.vulncheck.com/advisories/python-markdown-3.0-through-3.11.2-denial-of-service-via-link-bracket-parsing
• Referencehttps://github.com/Python-Markdown/markdown
• Referencehttps://github.com/Python-Markdown/markdown/blob/b41e0aaf1181f1a8cb200cf5a815aad7c0020d23/markdown/inlinepatterns.py#L1155-L1172
• Referencehttps://github.com/Python-Markdown/markdown/issues/1654
• Referencehttps://github.com/Python-Markdown/markdown/issues/798