Background Information

GHOST is a ‘buffer overflow’ bug affecting the gethostbyname() and gethostbyname2() function calls in the glibc library. This vulnerability allows a remote attacker that is able to make an application call to either of these functions to execute arbitrary code with the permissions of the user running the application.


The gethostbyname() function calls are used for DNS resolving, which is a very common event. To exploit this vulnerability, an attacker must trigger a buffer overflow by supplying an invalid hostname argument to an application that performs a DNS resolution.

Determining Vulnerability

As a Red Hat customer, the easiest way to check for the vulnerability and confirm remediation is the Red Hat Access Lab: glibc (GHOST) Detector. Please make sure that you have installed the correct version prior and if you are downloading the package for RHEL 4, you must be subscribed to the ELS channel or have downloaded the ELS version of the package. The RHEL 4 non-ELS subscription version will show a “vulnerable” message.