CVE-2026-59928

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, 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/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69	Patch
https://github.com/lepture/mistune/releases/tag/v3.3.0	Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q	Exploit Third Party Advisory
https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q	Exploit Third Party Advisory

Configurations

Configuration 1 (hide)

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

History

No history.

Information

Published : 2026-07-08 17:17

Updated : 2026-07-09 19:29

NVD link : CVE-2026-59928

Mitre link : CVE-2026-59928

CVE.ORG link : CVE-2026-59928

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-407

Inefficient Algorithmic Complexity

CWE-1333

Inefficient Regular Expression Complexity

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