Mistune TOC Anchor Injection XSS_CVE-2026-44898

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, render_toc_ul() builds a <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="#<id>") and the text value (used as the visible link label) are inserted into <a> tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href="#..." attribute context, injecting arbitrary HTML tags including <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.

Basic Information

ID CVE-2026-44898

Source GitHub_M

Published May 26, 2026 at 20:41

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": "2026-05-26T20:41:53.805Z",
    "modified": "2026-05-26T20:41:53.805Z",
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