CVE-2026-86435
commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote
- State
- Published
- Severity
- 8.7 High
- Published
- Sep 7, 2026
- Updated
- Oct 8, 2026
- Reserved
- Sep 7, 2026
Description
commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.
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 |
|---|---|
commonmarkthephpleague |
|
References
- GitHub Security Advisory (GHSA-jfm3-95jq-q3rf)vendor-advisory
- VulnCheck Advisory: commonmark 1.5.0 before 2.8.4 Denial of Service via Footnotethird-party-advisory
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