CVE-2026-76098

Mistune has Denial of Service — RecursionError via Excessive Emphasis Markers in Markdown

Published Aug 24, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
Mistune is a Python Markdown parser with renderers and plugins. Versions 3.3.0 through 3.3.2 are vulnerable to DoS through deeply nested tokens. HTML rendering creates deeply nested emphasis tokens from consecutive asterisk characters, and recursive rendering in HTMLRenderer.render_token() can exceed Python's recursion limit and raise RecursionError, allowing crafted Markdown to crash a parsing process. This issue is fixed in version 3.3.3

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-6m44-fpc8-c3rq Mistune: Denial of Service — RecursionError via Excessive Emphasis Markers in Markdown
History
Type Values Removed Values Added
First Time appeared Lepture
Lepture mistune
Vendors & Products Lepture
Lepture mistune
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Mistune is a Python Markdown parser with renderers and plugins. Versions 3.3.0 through 3.3.2 are vulnerable to DoS through deeply nested tokens. HTML rendering creates deeply nested emphasis tokens from consecutive asterisk characters, and recursive rendering in HTMLRenderer.render_token() can exceed Python's recursion limit and raise RecursionError, allowing crafted Markdown to crash a parsing process. This issue is fixed in version 3.3.3
Title Mistune has Denial of Service — RecursionError via Excessive Emphasis Markers in Markdown
Weaknesses CWE-674
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 24, 2026, 8:17 PM
Reserved
Aug 18, 2026, 9:17 PM
Status
Deferred
Published
Aug 24, 2026, 8:17 PM
Modified
Oct 12, 2026, 3:10 PM
Severity
Important
Public date
Aug 24, 2026, 8:05 PM