The XPConnect component in Mozilla Firefox before 2.0.0.17 and 3.x before 3.0.2, Thunderbird before 2.0.0.17, and SeaMonkey before 1.1.12 allows remote attackers to "pollute XPCNativeWrappers" and execute arbitrary code with chrome privileges via vectors related to (1) chrome XBL and (2) chrome JS.