CVE-2026-44899
Severity CVSS v4.0:
Pending analysis
Type:
CWE-79
Cross-Site Scripting (XSS)
Publication date:
26/05/2026
Last modified:
26/05/2026
Description
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.
Impact
Base Score 3.x
4.70
Severity 3.x
MEDIUM