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.

PUBLISHED Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-08 | Assigner GitHub_M

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

References

github.com/...istune/security/advisories/GHSA-8c25-4j27-2rv3 exploit

github.com/...istune/security/advisories/GHSA-8c25-4j27-2rv3

github.com/...ommit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc

github.com/lepture/mistune/releases/tag/v3.3.0

cve.org (CVE-2026-59923)

nvd.nist.gov (CVE-2026-59923)

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