The host is installed with Mozilla Firefox before 39.0, Firefox ESR 38.x before 38.1, Thunderbird before 31.8 or 38.x before 38.1 and is prone to an use-after-free vulnerability. A flaw is present in the applications, which fail to handle client-side JavaScript that triggers removal of a DOM object on the basis of a Content Policy. Successful exploitation could allow attackers to execute arbitrary code.