Mozilla Firefox before 3.0.19, 3.5.x before 3.5.9, and 3.6.x before 3.6.2, and SeaMonkey before 2.0.4, does not prevent applets from interpreting mouse clicks as drag-and-drop actions, which allows remote attackers to execute arbitrary JavaScript with Chrome privileges by loading a chrome: URL and then loading a javascript: URL.
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.