Web browsers using the Java 7 plug-in are at high risk.

IcedTea 2.3.0 (based on OpenJDK 7) is also affected.

A vulnerability in the way Java 7 restricts the permissions of Java applets could allow an attacker to execute arbitrary commands on a vulnerable system.

A vulnerability in the Java Security Manager allows a Java applet to grant itself permission 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 applet.

Any web browser using the Java 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#636312.