Improperly Controlled Modification of Dynamically-Determined Object Attributes Affecting mdast-util-to-hast package, versions >=13.0.0 <13.2.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsSnyk Learn
Learn about Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerabilities in an interactive lesson.
Start learning- Snyk IDSNYK-JS-MDASTUTILTOHAST-14157221
- published3 Dec 2025
- disclosed1 Dec 2025
- creditUnknown
Introduced: 1 Dec 2025
NewCVE-2025-66400 (opens in a new tab)How to fix?
Upgrade mdast-util-to-hast to version 13.2.1 or higher.
Overview
mdast-util-to-hast is a mdast utility to transform to hast
Affected versions of this package are vulnerable to Improperly Controlled Modification of Dynamically-Determined Object Attributes in the class attribute in rendered markdown code elements. An attacker can cause arbitrary CSS classes to be applied to elements by injecting specially crafted character references, altering the appearance or behavior of rendered content.