Using the eval associated with methods of an XBL binding it was possible to create JavaScript functions that would get compiled with the wrong privileges, allowing the attacker to run code of their choice with the full permission of the user running the browser. This could be used to install spyware or viruses.
Thunderbird shares the JavaScript engine with Firefox and could be vulnerable if JavaScript were to be enabled in mail. This is not the default setting and we strongly discourage users from running JavaScript in mail.
Disable JavaScript until you can upgrade to a fixed version.
Exploit code and details embargoed during the active update period.