CVE-2026-118694
python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users…
- Risk score
- 60/100
- CVSS
- 7.5 v3.1
- Published
- 28 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 q…
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Amber
- CVSS 7.5 high
- Remotely exploitable without logging in
- On your watchlist: python
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
- https://www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations
Original 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.
Last activity 28 Oct 2026. Patch Forecast updates every hour.