A bug lets a simple C program crash the kernel, effectively locking the whole system. Affects both 2.4.2x and 2.6.x kernels on the x86 architecture.

Not good at all and what makes it worse........

Using this exploit to crash Linux systems requires the (ab)user to have shell access. The program works on any normal user account, root access is not required.

Not all distro's affected

Full article -