CVE-2026-59925

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.

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/5de41fb8e527004dbc363e047a3c380c9288c74f	Patch
https://github.com/lepture/mistune/releases/tag/v3.3.0	Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

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

History

09 Jul 2026, 19:39

Type	Values Removed	Values Added
References	~~() https://github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74f -~~	() https://github.com/lepture/mistune/commit/5de41fb8e527004dbc363e047a3c380c9288c74f - Patch
References	~~() https://github.com/lepture/mistune/releases/tag/v3.3.0 -~~	() https://github.com/lepture/mistune/releases/tag/v3.3.0 - Release Notes
References	~~() https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45 -~~	() https://github.com/lepture/mistune/security/advisories/GHSA-4j32-57v6-6g45 - Exploit, Vendor Advisory
CPE		cpe:2.3:a:mistune_project:mistune::::::::
First Time		Mistune Project Mistune Project mistune

08 Jul 2026, 17:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-08 17:17

Updated : 2026-07-09 19:39

NVD link : CVE-2026-59925

Mitre link : CVE-2026-59925

CVE.ORG link : CVE-2026-59925

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-407

Inefficient Algorithmic Complexity

CWE-1333

Inefficient Regular Expression Complexity

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