Sorry guys this is a little delayed. I have been extremely busy.

A flaw in Netscape Communicator's implementation of Java allows malicious applets to read any resource reachable via a URL from the local machine by using the netscape.net.URLConnection and netscape.net.URLInputSteam classes. This allows malicious applets to read local files as well as download data from hosts that would otherwise could be protected by a firewall.

An untrusted applet normally is no allowed to read or write to the local file system, or to open network connections to any machine other than that from which it was downloaded.. Security sensitive classes such as FileInputStream() , RandomAccessFile(), or Socket() normally check whether a class can read from a local file by calling the SecurityManager.checkRead() method or whether it connect to other hosts by calling the SecurityManager.checkConnect() method.

Netscape's netscape.net.URLConnection and netscape.net.URLInputStream classes seem to ignore or not perform these checks when passed an URLs. Thus malicious classes and read local files using URLs of the type "file://".

If the machine running the malicious applet is behind a firewall it will also be able to download resources that can be accessed via a URL, such as web server ("http://" or "https://) or FTP servers ("ftp://"), that the attacker in control of the machine from which the applet was downloaded could not. In this way a malicious applet could be used to penetrate a firewall.

Basically this turns Netscape into a file server. Check out http://www.brumleve.com/BrownOrifice/ for an interesting exploit.

Update
 

Netscape released 4.75 which should fix the problem. It is available at ftp://ftp.netscape.com/pub/communica...plete_install/.

Well that's good to know, but the real question is will you use Internet Explorer for Linux when it's released? =)

Probably not. But I probably won't use netscape either. Mozilla is getting more and more stable with every new milestone. By the time they release it, it may be the only browser I use. If you haven't tried it yet I highly recommend it.

Just a quick follow-up
 

After using Netscape 4.75 for a little while now I have to say it is considerably faster and quite a bit more stable (I was using 4.73 previously). I highly recommend the upgrade!