NextChat version 2.16.1 contains a client‑side cross‑site scripting (XSS) vulnerability in the Plugin Editor due to unsafe rendering of externally supplied OpenAPI plugin schema content. When a plugin schema is loaded from a remote URL, the returned content is stored in plugin.content and later rendered using React’s dangerouslySetInnerHTML without proper sanitization. An attacker can host a malicious OpenAPI schema containing HTML or JavaScript markup and trick a user into loading it through the Plugin Editor, resulting in arbitrary JavaScript execution in the NextChat origin. Successful exploitation allows access to JavaScript‑readable cookies and other client‑side data associated with the NextChat application.