---
id: CVE-2026-59925
aliases:
  - PYSEC-2026-2213
  - GHSA-4j32-57v6-6g45
title: >-
  Mistune is a Python Markdown parser with renderers and plugins. Prior to
  3.3.0, long sequences of well-formed double-asterisk or triple-a…
summary: >-
  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 becau…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: mistune
product: mistune
ecosystem: pip
affected:
  - mistune < 3.3.0
patched:
  - mistune 3.3.0
published: '2026-07-08'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/PYSEC-2026-2213'
references:
  - url: 'https://github.com/lepture/mistune/releases/tag/v3.3.0'
  - url: >-
      https://github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74f
  - url: 'https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45'
tags:
  - osv
  - pip
epss: 0.00644
epssPercentile: 0.48675
ingestedAt: '2026-07-13T18:58:08.163Z'
---

## Overview

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.

## Affected packages

- `mistune < 3.3.0`

## Remediation

Upgrade to a patched release:

- `mistune 3.3.0`