Tuesday, January 16th, Sun released an advisory regarding a vulnerability in processing GIF images in some versions of the Java Runtime Environment.
When running a Java applet from a web page using a vulnerable version of Java Runtime, an applet exploiting the vulnerability may escape Java's sandbox. This means that the Java applet would have exactly the same access to the file system and process execution as any native application.
Java vulnerabilities have been actively used by malicious web pages in the past, so it is quite possible that this new vulnerability will also be used.
So do make sure that your Java runtime is up to date, instructions are available at
Sun Advisory #102760.Note: Sun provides links to J2SE 5.0 Update 10 in their advisory.
Update Now