Mozilla security researcher moz_bug_r_a4 reported that an XBL binding, when attached to an unloaded document, can be used to violate the same-origin policy and execute arbitrary JavaScript within the context of a different website.
moz_bug_r_a4 also reported two vulnerabilities by which page content can pollute XPCNativeWrappers and run arbitary JavaScript with chrome priviliges.
Thunderbird shares the browser 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 a version containing these fixes can be installed.