The LookupGetterOrSetter function in js3250.dll in Mozilla Firefox before 3.5.14 and 3.6.x before 3.6.11, Thunderbird before 3.0.9 and 3.1.x before 3.1.5, and SeaMonkey before 2.0.9 does not properly support window.__lookupGetter__ function calls that lack arguments, which allows remote attackers to execute arbitrary code or cause a denial of service (incorrect pointer dereference and application crash) via vectors involving a "dangling pointer" and the JS_ValueToId function.