CVE-2026-59923

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.

CVSS Vector

References

• https://github.com/lepture/mistune/commit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc
• https://github.com/lepture/mistune/releases/tag/v3.3.0
• https://github.com/lepture/mistune/security/advisories/GHSA-8c25-4j27-2rv3
• https://github.com/lepture/mistune/security/advisories/GHSA-8c25-4j27-2rv3