Is CVE-2026-59923 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-59923?

CVE-2026-59923 has a CVSS v3 severity of MEDIUM (6.1).

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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.