Netscape 4.73 and earlier does not properly warn users about a potentially invalid certificate if the user has previously accepted the certificate for a different web site, which could allow remote attackers to spoof a legitimate web site by compromising that site's DNS information.
Netscape Communicator before version 4.73 and Navigator 4.07 do not properly validate SSL certificates, which allows remote attackers to steal information by redirecting traffic from a legitimate web server to their own malicious server, aka the "Acros-Suencksen SSL" vulnerability.
Netscape 4.73 and earlier follows symlinks when it imports a new certificate, which allows local users to overwrite files of the user importing the certificate.
A configuration in a web browser such as Internet Explorer or Netscape Navigator allows execution of active content such as ActiveX, Java, Javascript, etc.