CVE-2026-118694

Description

python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated '[a](' or '![a](' sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.

References

• https://github.com/trentm/python-markdown2
• https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L1478-L1492
• https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L3029
• https://github.com/trentm/python-markdown2/issues/750
• https://github.com/trentm/python-markdown2/pull/751