Whats the vulnerability?
A scenario has been identified through which a Java applet could escape the sandbox and be able to perform normally-unauthorized functions on a user’s computer. Exploiting the vulnerability would only be possible through a very carefully-managed series of steps, and could not happen accidentally. However, if a malicious web site operator hosted a Java applet that exploited this security vulnerability, it would be able to take virtually any action on the computer of a user who visited the site.