Buffer overflow in the sun.awt.windows.WDefaultFontCharset Java class implementation in Netscape 4.0 allows remote attackers to execute arbitrary code via an applet that calls the WDefaultFontCharset constructor with a long string and invokes the canConvert method.

Netscape Communicator 4.0 through 4.79 allows remote attackers to bypass JVM security and execute arbitrary Java code via an applet that loads user-supplied Java classes.

Mozilla 0.9.6 and earlier and Netscape 6.2 and earlier allows remote attackers to steal cookies from another domain via a link with a hex-encoded null character (%00) followed by the target domain.

Netscape Communicator 4.x allows attackers to use a link to steal a user's preferences, including potentially sensitive information such as URL history, e-mail address, and possibly the e-mail password, by redefining the user_pref() function and accessing the prefs.js file, which is stored in a directory with a predictable name.