The host is missing an important security update according to Mozilla advisory, MFSA2016-47. The update is required to fix an arbitrary code execution vulnerability. A flaw is present in the JavaScript .watch() method, which can be used to overflow the 32-bit generation count of the underlying HashMap, resulting in a write to an invalid entry. Successful exploitation allows remote attackers to execute arbitrary code or cause a denial of service (generation-count overflow, out-of-bounds HashMap write access, and application crash).