Log in Start free

Vulnerability · Published May 26, 2026 · Assigned by GitHub_M

CVE-2026-44896Mistune: XSS via unescaped figclass/figwidth in Figure directive

Medium 5.3

In plain English

A medium-severity cross-site scripting in mistune from lepture. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.3Medium
Exploit odds (30 days)0.2%top 90.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12mistuneno fix listedDEBIAN-CVE-2026-44896
Debian:13mistuneno fix listedDEBIAN-CVE-2026-44896
Debian:14mistuneno fix listedDEBIAN-CVE-2026-44896
PyPImistune3.2.1GHSA-58cw-g322-p94v
PyPImistune3.2.1PYSEC-2026-168
Ubuntu:22.04:LTSmistuneno fix listedUBUNTU-CVE-2026-44896
Ubuntu:24.04:LTSmistuneno fix listedUBUNTU-CVE-2026-44896
Ubuntu:25.10mistuneno fix listedUBUNTU-CVE-2026-44896
Ubuntu:26.04:LTSmistuneno fix listedUBUNTU-CVE-2026-44896
Ubuntu:26.10mistuneno fix listedUBUNTU-CVE-2026-44896
Ubuntu:22.04:LTSmistune0no fix listedUBUNTU-CVE-2026-44896
Ubuntu:24.04:LTSmistune0no fix listedUBUNTU-CVE-2026-44896
Ubuntu:25.10mistune0no fix listedUBUNTU-CVE-2026-44896
Ubuntu:26.04:LTSmistune0no fix listedUBUNTU-CVE-2026-44896
Ubuntu:26.10mistune0no fix listedUBUNTU-CVE-2026-44896

Affected products (as reported)

VendorProductVersions
lepture mistune < 3.2.1

Weakness: CWE-79 · 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

References