CVE-2026-59926
Medium
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.
SeverityMedium
CVSS6.1
Exploit probability—
ProductMistune
PublishedJul 8, 2026
First seenJul 8, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- mistune_project mistune3.3.0 or later
- mistune3.3.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mistune_project mistune | v < 3.3.0 | 3.3.0 |
| mistunePyPI | v < 3.3.0 | 3.3.0 |
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