OpenEMR is a free and open source electronic health records and medical practice management application. Prior to version 8.0.0.3, the POST parameter title is reflected back in a JSON response built with json_encode(). Because the response is served with a text/html Content-Type, the browser interprets injected HTML/script tags rather than treating the output as JSON. An authenticated attacker can craft a request that executes arbitrary JavaScript in a victim's session. Version 8.0.0.3 contains a fix.