CVE-2026-118694

CVE-2026-118694 · python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinations

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 8.7 · High · EPSS 0.5%

Published: 2026-10-28T21:11:20.814Z
Updated: 2026-10-28T21:11:20.814Z

Affected products and versions

python-markdown2
Versions
- ≥ 0, ≤ 2.5.5: Affected (custom)
No fix published

Original sources

https://github.com/trentm/python-markdown2/issues/750
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/pull/751
https://www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations
https://nvd.nist.gov/vuln/detail/CVE-2026-118694

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