Mozilla Firefox before 3.6.20, SeaMonkey 2.x, Thunderbird 3.x before 3.1.12, and possibly other products does not properly handle the dropping of a tab element, which allows remote attackers to execute arbitrary JavaScript code with chrome privileges by establishing a content area and registering for drop events.

Mozilla Firefox 4.x through 5, Thunderbird before 6, SeaMonkey 2.x before 2.3, and possibly other products, when the Direct2D (aka D2D) API is used on Windows, allows remote attackers to bypass the Same Origin Policy, and obtain sensitive image data from a different domain, by inserting this data into a canvas.