Mozilla security researcher moz_bug_r_a4 reported a vulnerability which allows scripts from page content to run with elevated privileges. Using this vulnerability, an attacker could cause a chrome privileged object, such as the browser sidebar or the FeedWriter, to interact with web content in such a way that attacker controlled code may be executed with the object's chrome privileges.
Thunderbird supports neither the sidebar nor BrowserFeedWriter objects and is not vulnerable in its default configuration. Thunderbird might be vulnerable if the user has installed any add-on which adds a similarly implemented feature and then enables JavaScript in mail messages. This is not the default setting and we strongly discourage users from running JavaScript in mail.
Disable JavaScript until a version containing this fix can be installed.