As many of you may have heard, there is a vulnerability nicknamed "Ghost" in the glibc library, which allows attackers to perform remote code execution on an unpatched server.
If you haven't already, we highly recommend updating your system.
You can do that by running
yum update on RHEL and CentOS, or
apt-get update && apt-get upgrade on Ubuntu and Debian.
After performing those updates, we'd suggest you reboot your server, though alternatively you could technically restart all the processes on your server relying on glibc (which is likely most of them).
You can read more about this vulberability here: