The POP3 mail client in Mozilla 1.0 and earlier, and Netscape Communicator 4.7 and earlier, allows remote attackers to cause a denial of service (no new mail) via a mail message containing a dot (.) at a newline, which is interpreted as the end of the message.

Mozilla 0.9.6 and earlier and Netscape 6.2 and earlier allows remote attackers to steal cookies from another domain via a link with a hex-encoded null character (%00) followed by the target domain.