Inefficient Algorithmic Complexity Affecting mistune package, versions [,3.3.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-MISTUNE-21460663
- published23 Oct 2026
- disclosed22 Oct 2026
- creditoffset
Introduced: 22 Oct 2026
NewCVE-2026-115352 (opens in a new tab)How to fix?
Upgrade mistune to version 3.3.0 or higher.
Overview
Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity via the _contains_nested_link method in src/mistune/inline_parser.py, where bracket parsing during inline link resolution triggers catastrophic backtracking. An attacker can supply input containing deeply nested or repeated bracket sequences that cause the parser to perform exponential work, crashing the process.