CVE-2026-59930
Medium
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable toc_N values without slugifying the heading text, allowing attacker-controlled id="toc_N" content to collide with generated anchors and redirect same-page navigation, CSS selectors, or JavaScript handlers. This issue is fixed in version 3.3.0.
SeverityMedium
CVSS4.3
Exploit probability—
ProductMistune
PublishedJul 8, 2026
First seenJul 8, 2026
Weakness typeCWE-345CWE-345CWE-1284CWE-1284
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 |
Check your version
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