Mozilla Firefox before 40.0 and Firefox ESR 38.x before 38.2 do not impose certain ECMAScript 6 requirements on JavaScript object properties, which allows remote attackers to bypass the Same Origin Policy via the reviver parameter to the JSON.parse method.
Exploitability
AV:NAC:LAu:NImpact
C:NI:PA:N5/AV:N/AC:L/Au:N/C:N/I:P/A:N