By default, Internet Explorer 5.0 and other versions enables the "Navigate sub-frames across different domains" option, which allows frame spoofing.
Internet Explorer 3.x to 4.01 allows a remote attacker to insert malicious content into a frame of another web site, aka frame spoofing.
When Javascript is embedded within the TITLE tag, Netscape Communicator allows a remote attacker to use the "about" protocol to gain access to browser information.
A remote attacker can read information from a Netscape user's cache via JavaScript.
JavaScript in Internet Explorer 3.x and 4.x, and Netscape 2.x, 3.x and 4.x, allows remote attackers to monitor a user's web activities, aka the Bell Labs vulnerability.