Mozilla security researcher moz_bug_r_a4 reported that
when non-priviliged XUL documents include scripts from chrome:
URIs used in the browser it was possible to take advantage of the privilege
level stored in the pre-compiled "fastload" file. This could allow an
attacker to run arbitrary JavaScript code with chrome privileges.
Thunderbird users are not at risk when JavaScript is disabled in mail. This is the default setting and we strongly discourage users from enabling JavaScript in mail.
Disable JavaScript until a version containing these fixes can be installed.