The host is missing an important security update according to Mozilla advisory, MFSA 2015-109. The update is required to fix an ECMAScript 5 (aka ES5) API protection mechanism bypass vulnerability. A flaw is present in the application, which fails to properly handle a crafted web page that does not use ES5 APIs. Successful exploitation could allow attackers to bypass certain ECMAScript 5 (aka ES5) API protection mechanisms and modify immutable properties.