CVE-2026-59929
Medium
Description
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:, and res: to reach rendered href and src attributes and potentially execute script in affected user agents. 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)CWE-184CWE-184
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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