Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Severity (CVSS)
| Base score | 7.5 |
|---|---|
| Severity | High |
| Version | CVSS 3.1 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Provided by | CNA |
Weaknesses
- CWE-407 — CWE-407: Inefficient Algorithmic Complexity
- CWE-1333 — CWE-1333: Inefficient Regular Expression Complexity
Affected products
| Vendor | Product | Versions |
|---|---|---|
| lepture | mistune | < 3.3.0 |
References
- https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q (x_refsource_CONFIRM)
- https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69 (x_refsource_MISC)
- https://github.com/lepture/mistune/releases/tag/v3.3.0 (x_refsource_MISC)
Generated from the official CVE List on 09 Jul 2026 07:08 UTC.