CVE-2026-118694
python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinations
- State
- Published
- Severity
- 8.7 High
- Published
- Oct 28, 2026
- Updated
- Oct 29, 2026
- Reserved
- Oct 28, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-407 Inefficient Algorithmic Complexity
Affected Products
| Product | Versions |
|---|---|
python-markdown2trentm |
|
References
- GitHub Issue #750issue-tracking
- https://github.com/trentm/python-markdown2product
- https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L1478-L1492technical-description
- https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L3029technical-description
- https://github.com/trentm/python-markdown2/pull/751patchissue-tracking
- VulnCheck Advisory: python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinationsthird-party-advisory
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.