CVE-2026-59926 | THREATINT

Description

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.

PUBLISHED Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-08 | Assigner GitHub_M

MEDIUM: 5.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

< 3.2.1

affected

References

github.com/...istune/security/advisories/GHSA-g97x-gvcm-x72h

github.com/...ommit/a3cb6e5655308797e8be021d6c7b5bab13cbace2

github.com/lepture/mistune/releases/tag/v3.2.1

cve.org (CVE-2026-59926)

nvd.nist.gov (CVE-2026-59926)

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