CVE-2026-59928
HIGH
NVD
CVSS Score
7.5
Severity
HIGH
Published
Jul 08, 2026
Vendor
unknown
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.