CVEvulnerability

CVE-2026-44898

6.1 MEDIUM Published 2026-05-26 Modified 2026-07-24 Official page ↗
Status
Analyzed
Published
2026-05-26
Last modified
2026-07-24
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.1 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weaknesses
CWE-79

Description

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.

Affected configurations

• mistune project mistune (< 3.2.1)

Related

Weakness · CWE (1)

  • CWE-79 Improper Neutralization of Input During Web Page Generation weakness

References