PT-2026-56511 · Pypi · Mistune

Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-59926

Positive Technologies (AI Summary)

CVSS v4.0

5.3

Medium

Base vector

AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Name of the Vulnerable Software and Affected Versions Mistune versions prior to 3.2.1

Description The render admonition() function in src/mistune/directives/admonition.py concatenates the :class: option of the Admonition directive into the HTML class attribute without proper escaping. This allows for attribute injection and cross-site scripting (XSS), a technique where malicious scripts are injected into trusted websites, even when the HTMLRenderer escape mode is active.

Recommendations Update to version 3.2.1.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-59926

Affected Products

Mistune

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-59926 · Security Note
• https://github.com/lepture/mistune/commit/a3cb6e5655308797e8be021d6c7b5bab13cbace2 · Note
• https://github.com/lepture/mistune/releases/tag/v3.2.1 · Note
• https://github.com/lepture/mistune/security/advisories/GHSA-g97x-gvcm-x72h · Note
• https://twitter.com/infoflowcloud/status/2074933101256446376 · Twitter Post
• https://twitter.com/CVEnew/status/2074931630028812298 · Twitter Post