Mozilla Firefox 2.x before 2.0.0.18, Thunderbird 2.x before 2.0.0.18,
and SeaMonkey 1.x before 1.1.13 do not properly change the source URI
when processing a canvas element and an HTTP redirect, which allows
remote attackers to bypass the same origin policy and access arbitrary
images that are not directly accessible to the attacker. NOTE: this
issue can be leveraged to enumerate software on the client by
performing redirections related to moz-icon.