Mistune Heading ID Attribute Injection XSS_CVE-2026-44897

6.1 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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.

Basic Information

ID CVE-2026-44897

Source GitHub_M

Published May 26, 2026 at 20:40

Affected Product

Vendor lepture

Product mistune

Version < 3.2.1

Affected Versions lepture mistune < 3.2.1

CWE Classification

CWE-79

References

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    "published": "2026-05-26T20:40:42.290Z",
    "modified": "2026-05-26T20:40:42.290Z",
    "type": "cve",
    "title": "Mistune Heading ID Attribute Injection XSS",
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    "references": "https://github.com/lepture/mistune/security/advisories/GHSA-v87v-83h2-53w7\nhttps://github.com/lepture/mistune/releases/tag/v3.2.1",
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