CVE-2026-44896CWE-79

Mistune: XSS via unescaped figclass/figwidth in Figure directive

Medium · published May 26, 2026

CVSS v4.0
5.3
EPSS
0%
Percentile
18.3
In the wild
Unconfirmed
What it is

Mistune is a Python Markdown parser with renderers and plugins. In 3.2.0 and earlier, in src/mistune/directives/image.py, the render_figure() function concatenates figclass and figwidth options directly into HTML attributes without escaping. This allows attribute injection and XSS even when HTMLRenderer(escape=True) is used, because these values bypass the inline renderer. Version 3.2.1 contains a patch.

The record
Technical detail
CVSS v4.0
5.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
EPSS
0.00271 · 18.3th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-05-26T20:33Z
EPSS history
Timeline
  • 26 MAY 20:33Z
    Mistune: XSS via unescaped figclass/figwidth in Figure directive
    cvelistv5