6.9
Medium
CVE-2026-121438 Mistune before 3.3.3 contains a denial of service vulnerability in InlineParser.parse_link that allows attackers to…
Description
Mistune before 3.3.3 contains a denial of service vulnerability in InlineParser.parse_link that allows attackers to cause quadratic CPU growth by supplying balanced nested brackets. Attackers can submit crafted Markdown with thousands of nested bracket pairs not forming a valid link, triggering repeated _contains_nested_link scans that exhaust CPU in parsing applications.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| mistune 3.3 | earliest → < 3.3.3 | 3.3.3 |
References
- GitHub Security Advisory (GHSA-47p6-w2rc-5qf7) github.com
- Patch Commit github.com
- VulnCheck Advisory: Mistune before 3.3.3 Denial of Service via Balanced Bracket Link Parsing www.vulncheck.com
Timeline
- Published
- Last modified
Other CVEs of mistune
The 28 CVEs of mistune →
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…
8.7
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CVE-2026-115354
Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to…
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