ZendTo contains a flaw that allows a stored cross-site scripting (XSS) attack. This flaw exists because the application does not validate the 'emailAddr' parameter upon submission to the pickup.php script which is then passed to the lib/NSSDropoff.php script. This may allow an attacker to create a specially crafted request that would execute arbitrary script code in a user's browser within the trust relationship between their browser and the server.