The host is installed with Mozilla Firefox 4.x through 11.0, Firefox ESR 10.x before 10.0.4, Thunderbird 5.0 through 11.0, Thunderbird ESR 10.x before 10.0.4, or SeaMonkey before 2.9 and is prone to address bar spoofing vulnerability. A flaw is present in the applications, which fail to properly load RSS and Atom feed content. Successful exploitation could allow attackers to spoof the address bar.