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.

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 Navigator uses weak encryption for storing a user's Netscape mail password.

Netscape Mail Notification (nsnotify) utility in Netscape Communicator uses IMAP without SSL, even if the user has set a preference for Communicator to use an SSL connection, allowing a remote attacker to sniff usernames and passwords in plaintext.

Netscape 4.7 records user passwords in the preferences.js file during an IMAP or POP session, even if the user has not enabled "remember passwords."

Buffer overflow in Netscape Navigator/Communicator 4.7 for Windows 95 and Windows 98 allows remote attackers to cause a denial of service, and possibly execute arbitrary commands, via a long argument after the ? character in a URL that references an .asp, .cgi, .html, or .pl file.