CVE-2026-44897

6.1 MEDIUM

Mistune is a Python Markdown parser with renderers and plugins

Published: 2026-05-26 · Last updated: 2026-05-28

Severity and scoring

CVSS: 6.1 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE: CWE-79

Affected products

Vendor	Product
mistune_project	mistune

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening <hN> tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-44897
[Other]https://github.com/lepture/mistune/releases/tag/v3.2.1
[Vendor advisory]https://github.com/lepture/mistune/security/advisories/GHSA-v87v-83h2-53w7

Related CVEs

Same vendor

CVE-2026-44899 — Mistune is a Python Markdown parser with renderers and plugins (4.7 MEDIUM)
CVE-2026-44898 — Mistune is a Python Markdown parser with renderers and plugins (6.1 MEDIUM)
CVE-2026-44896 — Mistune is a Python Markdown parser with renderers and plugins (6.1 MEDIUM)
CVE-2026-44708 — Mistune is a Python Markdown parser with renderers and plugins (6.1 MEDIUM)

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