CVE-2026-76098: CWE-674: Uncontrolled Recursion in lepture mistune
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
CVSS v3.1
Score 7.5high
Affected software
lepture
mistune
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-76098 affects Mistune versions 3.3.0 to 3.3.2, where the HTMLRenderer.render_token() function recursively processes deeply nested emphasis tokens generated from consecutive asterisk characters in Markdown input. This uncontrolled recursion can exceed Python's recursion limit, causing a RecursionError and resulting in a denial-of-service condition by crashing the parser. The vulnerability is classified under CWE-674 (Uncontrolled Recursion). The issue is resolved in Mistune version 3.3.3.
Potential Impact
An attacker can craft Markdown content with deeply nested emphasis tokens that cause the parser to exceed the recursion limit, triggering a RecursionError and crashing the parsing process. This leads to a denial-of-service (DoS) condition, impacting availability of services relying on Mistune for Markdown parsing. There is no impact on confidentiality or integrity.
Mitigation Recommendations
Upgrade Mistune to version 3.3.3 or later, where this uncontrolled recursion vulnerability has been fixed. No other mitigation is indicated or required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-18T21:17:32.201Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a8ca814acd9273b49150585
Added to database: 08/24/2026, 20:22:44 UTC
Last enriched: 08/24/2026, 20:37:05 UTC
Last updated: 10/06/2026, 18:48:25 UTC
Views: 58
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