How To Protect Your Linux Server from the GHOST Vulnerability

GHOST vulnerability affecting Linux systems was discovered in the C library of GNU / Linux (glibc) that gives control to attackers without requiring system credentials.


GHOST creates a buffer overflow that affects all the gethostbyname*() functions in the glibc library. These functions change a hostname into an IP addresses. A hacker exploiting this can gain complete access of the Linux machine.

To verify you are running the updated packages, run the following commands:

rpm -qa glibc
rpm -qa nscd


The updated versions for CentOS 5 and 6 are shown below:

CentOS 5:



CentOS 6:



Not on these versions of CentOS? Run “yum update glibc nscd” to update the package.

A server reboot is recommended to ensure that all services begin using the new packages. If a reboot is not possible, most processes should be restarted on the server.

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