VULNERABILITY INTELLIGENCE

CVE-2026-59928

CVSS score7.5 HIGH
EPSS probability0.65%
CISA KEVNot currently listed
Published2026-07-08
Last modified2026-10-25
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Weakness classification

  • security-advisories@github.com: CWE-407

Primary references