CVE-2026-121438
Last modified
CVE-2026-121438 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.
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.
Metrics
Weakness Enumeration
References
Timeline
- Published
- Last Modified
- Status
- Deferred
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