PDF.js in Mozilla Firefox before 39.0 and Firefox ESR 31.x before 31.8 and 38.x before 38.1 enables excessive privileges for internal Workers, which might allow remote attackers to execute arbitrary code by leveraging a Same Origin Policy bypass.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:P7.5/AV:N/AC:L/Au:N/C:P/I:P/A:P