Under... SELinux standing !

Security-enhanced Linux (SELinux) is an implementation of a mandatory access control (MAC) mechanism. This mechanism is in the Linux kernel, checking for allowed operations after standard Linux discretionary access controls are checked.
Standard Linux security is a discretionary access control model (DAC).

Discretionary access control (DAC)

DAC is standard Linux security, and it provides no protection from broken software or malware running as a normal user or root.

What does Exploit means ?
Exploit is a very small program that when utilized causes a software vulnerability to be triggered and leveraged by the attacker.

What does Buffer Overflows means ?
Buffer Overflow occurs when a buffer that has been allocated a specific storage space has more data copied to it than it can handle.

So...
Have you checked your server's log files lately ???
Did you notice something like... this !!!