An unknown vulnerability was discovered in Linux kernel, which allows an attacker to gain root-access in Linux 2.6.37 - 3.8.8. The problem existed for the last two or three years and was present in all kernels.
Exploit for the vulnerability is publicly available. Anyone can compile and run it on any system, checking its operation. Exploit shall operate on 2.6.37 kernels – 3.8.8 compiled with PERF_EVENTS.
Linux Foundation knew about the vulnerability and in April this year released a patch for kernel version 3.8.9. Other distributions remain unpatched, particularly Ubuntu and Debian Wheezy.