CVE-2026-59922

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/lepture/mistune/commit/96d0f57f8fe9eeb06bb4cff521962a27d7c402e7	Patch
https://github.com/lepture/mistune/releases/tag/v3.3.0	Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq	Exploit Vendor Advisory
https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

History

25 Oct 2026, 17:10

Type	Values Removed	Values Added
Summary		(es) Mistune es un analizador de Markdown en Python con renderizadores y plugins. Antes de la versión 3.3.0, una secuencia de pares de marcadores cerrados de tilde, signo de igual o acento circunflejo alrededor de un carácter causa un trabajo cuadrático en src/mistune/plugins/formatting.py cuando el plugin de tachado, marcado o inserción busca marcadores coincidentes desde cada posible posición de inicio, permitiendo la denegación de servicio por agotamiento de la CPU. Este problema se ha solucionado en la versión 3.3.0.

Information

Published : 2026-07-08 17:17

Updated : 2026-10-25 17:10

NVD link : CVE-2026-59922

Mitre link : CVE-2026-59922

CVE.ORG link : CVE-2026-59922

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-407

Inefficient Algorithmic Complexity

CWE-1333

Inefficient Regular Expression Complexity

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