The security check in js_ValueToFunctionObject() can be bypassed by clever use of setTimeout() and the new Firefox 1.5 array method ForEach. shutdown demonstrated how to leverage this into a privilege escalation vulnerability that would allow the installation of malware.
This vulnerability was introduced during Firefox 1.5 development, Firefox 1.0 and Mozilla Suite 1.7 are not affected.
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 you upgrade to a fixed version.
Exploit code and details embargoed during the active update period.