CVE-2026-59923
Medium
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.
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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