CVE-2026-59928Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions

Descripción

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.

Datos: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Se publican tal como los indican las fuentes, en inglés.

Productos y versiones afectados

Referencias y parches

• https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q ExploitThird Party Advisory
• https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69 Patch
• https://github.com/lepture/mistune/releases/tag/v3.3.0 Release Notes