Mozilla Firefox before 3.6.23 and 4.x through 6, Thunderbird before 7.0, and SeaMonkey before 2.4 do not prevent the starting of a download in response to the holding of the Enter key, which allows user-assisted remote attackers to bypass intended access restrictions via a crafted web site.

Mozilla Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.5, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.5, and SeaMonkey before 2.10 allow local users to obtain sensitive information via an HTML document that loads a shortcut (aka .lnk) file for display within an IFRAME element, as demonstrated by a network share implemented by (1) Microsoft Windows or (2) Samba.

Mozilla Firefox 4.x through 11.0, Thunderbird 5.0 through 11.0, and SeaMonkey before 2.9 do not properly construct the Origin and Sec-WebSocket-Origin HTTP headers, which might allow remote attackers to bypass an IPv6 literal ACL via a cross-site (1) XMLHttpRequest or (2) WebSocket operation involving a nonstandard port number and an IPv6 address that contains certain zero fields.

Mozilla Firefox 4.x through 9.0 and SeaMonkey before 2.7 on Linux and Mac OS X set weak permissions for Firefox Recovery Key.html, which might allow local users to read a Firefox Sync key via standard filesystem operations.