The Script.prototype.freeze/thaw functionality in Mozilla 1.4 and earlier allows attackers to execute native methods by modifying the string used as input to the script.thaw JavaScript function, which is then deserialized and executed.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2003-0782
https://bugzilla.mozilla.org/show_bug.cgi?id=221526
http://www.securityfocus.com/bid/9322
http://www.securityfocus.com/advisories/6979
http://www.mandriva.com/security/advisories?name=MDKSA-2004:021