Sun Java Media Framework (JMF) 2.1.1 through 2.1.1c allows unsigned applets to cause a denial of service (JVM crash) and read or write unauthorized memory locations via the ReadEnv class, as demonstrated by reading environment variables using modified .data and .size fields.
http://www.illegalaccess.org/java/jmf.php
http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsalert%2F54760
http://securitytracker.com/id?1006777
http://archive.cert.uni-stuttgart.de/bugtraq/2003/06/msg00219.html