CVE-2025-66400

mdast-util-to-hast unsanitized class attribute

State: Published
Severity: 6.9 Medium
Published: Dec 1, 2025
Updated: Dec 2, 2025
Reserved: Nov 28, 2025

Description

mdast-util-to-hast is an mdast utility to transform to hast. From 13.0.0 to before 13.2.1, multiple (unprefixed) classnames could be added in markdown source by using character references. This could make rendered user supplied markdown code elements appear like the rest of the page. This vulnerability is fixed in 13.2.1.

Scores

CVSS	Score	Vector	Source
4.0	6.9 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-20 Improper Input Validation
CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes

Affected Products

Product	Versions
mdast-util-to-hastsyntax-tree	>= 13.0.0, < 13.2.1Affected

References

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