CVE-2026-59923: Mistune Project Mistune

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Mistune Project Mistune: before 3.3.0 (fixed in 3.3.0)

Published 2026-07-08. Last modified 2026-07-09.