Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mistune Project | Mistune | < 3.3.0 |
Related Weaknesses (CWE)
References
- https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87cPatch
- https://github.com/lepture/mistune/releases/tag/v3.3.0Release Notes
- https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92qExploitThird Party Advisory
- https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92qExploitThird Party Advisory
FAQ
What is CVE-2026-59928?
CVE-2026-59928 is a vulnerability with a CVSS score of 7.5 (HIGH). 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...
How severe is CVE-2026-59928?
CVE-2026-59928 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59928?
Check the references section above for vendor advisories and patch information. Affected products include: Mistune Project Mistune.