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.

By default, Internet Explorer 5.0 and other versions enables the "Navigate sub-frames across different domains" option, which allows frame spoofing.

The byte code verifier component of the Java Virtual Machine (JVM) allows remote execution through malicious web pages.