CVE-2026-59926

EUVD-2026-42334
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.
Cross-site Scripting
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
6.1 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 8.82%
Affected Products (NVD)
VendorProductVersion
mistune_projectmistune
𝑥
< 3.3.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
mistune
bookworm
2.0.4-1
fixed
bullseye
0.8.4-4
fixed
forky
vulnerable
sid
vulnerable
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
mistune
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
Azure Linux logo
Azure Linux Releases
Azure Package
Release
python-mistune
Azure Linux 3.0
0:3.3.0-1.azl3
fixed
Common Weakness Enumeration
References
https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2
https://github.com/lepture/mistune/releases/tag/v3.2.1
https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h