Netscape Communicator 4.6 Win95 (probably all 4.x) allows code injection in the "about:" protocol.
The problem is injecting JS code in "charset" and then executing it after opening "about:document".
Vulnerabilities:
Reading user's cache
Reading Netscape's configuration ("about:config") including user's email address, mail servers and password.
Probably others

This page demonstrates reading the first URL in your cache.
(The source is so complex because you cannot use ";")

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