Mozilla Firefox before 3.5.16 and 3.6.x before 3.6.13, and SeaMonkey before 2.0.11, does not properly handle certain redirections involving data: URLs and Java LiveConnect scripts, which allows remote attackers to start processes, read arbitrary local files, and establish network connections via vectors involving a refresh value in the http-equiv attribute of a META element, which causes the wrong security principal to be used.