Reliance on Untrusted Inputs in a Security Decision Affecting katex package, versions >=0.11.0 <0.18.2
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 applications- Snyk IDSNYK-JS-KATEX-20419402
- published4 Oct 2026
- disclosed1 Oct 2026
- creditJoost Grunwald
Introduced: 1 Oct 2026
NewCVE-2026-103923 (opens in a new tab)How to fix?
Upgrade katex to version 0.18.2 or higher.
Overview
katex is a Fast math typesetting for the web.
Affected versions of this package are vulnerable to Reliance on Untrusted Inputs in a Security Decision via the applySetting function in src/Settings.ts and the get/set methods in src/Namespace.ts, where user-controlled option keys and macro names are read from plain objects without hasOwnProperty guards. An attacker who can supply a rendered LaTeX string containing a macro or setting key such as __proto__ can pollute Object.prototype, affecting all objects in the runtime and potentially enabling cross-site scripting or other downstream impacts.