CVE-2026-59923: 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 M
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-59923
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-599230.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 10% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-59923 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for Mistune is a
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- highGHSA-qcq2-496w-v96p: Mistune: Potential DoS via quadratic-time parsing in parse_link_textghsa · 2026-07-09
- mediumCVE-2026-59930: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin…nvd · 2026-07-08
- mediumCVE-2026-59929: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url f…nvd · 2026-07-08
- highCVE-2026-59928: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown doc…nvd · 2026-07-08
- mediumCVE-2026-59927: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include di…nvd · 2026-07-08
- mediumCVE-2026-59926: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonit…nvd · 2026-07-08
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