CVE-2026-44898

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="#<id>") and the text value (used as the visible link label) are inserted into <a> tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href="#..." attribute context, injecting arbitrary HTML tags including <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/lepture/mistune/releases/tag/v3.2.1	Product Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-6269-cqxg-mhhv	Exploit Vendor Advisory
https://github.com/lepture/mistune/security/advisories/GHSA-6269-cqxg-mhhv	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

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

History

No history.

Information

Published : 2026-05-26 21:16

Updated : 2026-07-24 11:10

NVD link : CVE-2026-44898

Mitre link : CVE-2026-44898

CVE.ORG link : CVE-2026-44898

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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