Cloudanix VulnDB

CVE-2026-44899

Medium · 4.7

CVSS

4.7

EPSS

0.3%

Published

May 26, 2026

CISA due date

—

The record

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as _num_re = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, render_block_image() inserts it directly into a style="width:...;" or style="height:...;" attribute. Because the value was accepted by the prefix-only regex, any CSS after the leading digits reaches the style= attribute verbatim and without escaping. This vulnerability is fixed in 3.2.1.

Affected packages

Ecosystem Package Introduced Fixed

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