8.7
High
CVE-2026-121437 Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU…
Description
Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU through quadratic-time emphasis delimiter processing. Attackers can submit small markdown documents with repeated patterns like "*a_b" to trigger an O(n²) index-fixup loop, stalling workers for seconds.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| mistune 3.3 | 3.3.0 → < 3.3.4 | 3.3.4 |
References
- GitHub Security Advisory (GHSA-qp42-r9j6-83g9) github.com
- Patch Commit github.com
- VulnCheck Advisory: Mistune 3.3.0 before 3.3.4 Quadratic-Time DoS via _process_emphasis_delimiters www.vulncheck.com
Timeline
- Published
- Last modified
Other CVEs of mistune
The 28 CVEs of mistune →
CVE-2026-121438
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6.9
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CVE-2026-115354
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7.1
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CVE-2026-115355
Mistune before 3.3.0 contains a path traversal vulnerability in the Include directive that allows attackers to read…
8.7
High
CVE-2026-115353
Mistune before 3.3.0 Path Traversal via include Directive
9.2
Critical