CVE 2012-0455
Mozilla Firefox before 3.6.28 and 4.x through 10.0, Firefox ESR 10.x before 10.0.3, Thunderbird before 3.1.20 and 5.0 through 10.0, Thunderbird ESR 10.x before 10.0.3, and SeaMonkey before 2.8 do not properly restrict drag-and-drop operations on javascript: URLs, which allows user-assisted remote attackers to conduct cross-site scripting (XSS) attacks via a crafted web page, related to a "DragAndDropJac
See the 
CVE page on Mitre.org
for more details.
