CVE-2026-59925 — inline_parser: quadratic-time parsing on long runs of `**x**` and `***x***` emphasis pairs
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a characte…
Published: 2026-07-08 · CVSS: 7.5 · CVSS 3.1
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7