What’s Vulnerable › Vulnerabilities

CVE-2026-44708: Mistune Math Plugin XSS Escape Bypass

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-26 · updated 2026-07-24
• Weakness: CWE-79

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the mistune math plugin renders inline math ($...$) and block math ($$...$$) by concatenating the raw user-supplied content directly into the HTML output without any HTML escaping. This occurs even when the parser is explicitly created with escape=True, which is supposed to guarantee that all user-controlled text is sanitised before reaching the DOM. This vulnerability is fixed in 3.2.1.

Affected products

• lepture mistune: before 3.2.1 — fixed in 3.2.1

How to fix

Upgrade to a fixed version: lepture mistune 3.2.1. Check the vendor advisory for mitigations.

References

• https://github.com/lepture/mistune/releases/tag/v3.2.1
• https://github.com/lepture/mistune/security/advisories/GHSA-8g87-j6q8-g93x
• https://github.com/lepture/mistune/security/advisories/GHSA-8g87-j6q8-g93x

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