Mozilla Firefox and Thunderbird 1.x before 1.5 and 1.0.x before 1.0.8, Mozilla Suite before 1.7.13, and SeaMonkey before 1.0 does not properly protect the compilation scope of privileged built-in XBL bindings, which allows remote attackers to execute arbitrary code via the (1) valueOf.call or (2) valueOf.apply methods of an XBL binding, or (3) "by inserting an XBL method into the DOM's document.body prototype chain."