KaTeX uses ordinary JavaScript property access for the renderer options object, the trust setting, default and processor setting metadata, and namespace lookup and group restoration. This allows inherited properties to be treated as explicitly supplied values. If `Object.prototype` is polluted or an attacker controls the options object's prototype, attacker-controlled mathematical expressions can use an inherited trust value to enable trusted rendering. This can lead to user-interaction cross-site scripting (XSS)—a technique where malicious scripts are injected into trusted websites—or the loading of attacker-selected external resources in applications that insert unsanitized KaTeX output into a page. KaTeX does not create the prototype pollution itself, and rendering an expression alone does not execute script.