A few days ago a reliable privileged escalation vulnerability was found in recent versions of the Linux kernel. Point and click exploits are showing up around the web and someone even created an Android version. Exploitation requires that attackers have access to a non privileged account; thus systems with many users are at the highest risk.
The vulnerability effects kernel version kernel version 2.6.39 and above. To check which version of the Linux kernel you are running use the command uname -a. If you are running Red Hat Enterprise Linux version 6 kernel 2.6.32-220.el6 and above are vulnerable.
George Moore, Information Security Architect
Brandeis LTS Information Security