An arbitrary memory read and write vulnerability in the Java JVM process could allow an attacker to execute arbitrary code. An attacker could use social engineering techniques to entice a user to visit a link to a website hosting a malicious Java applet. An attacker could also compromise a legitimate website and upload a malicious Java applet (a "drive-by download" attack).
Any web browser using the Java 5, 6, or 7 plug-in is affected. The Java Deployment Toolkit plug-in and Java Web Start can also be used as attack vectors.
Reports indicate this vulnerability is being actively exploited, and exploit code is publicly available.
Further technical details are available in Vulnerability Note VU#688246.