On January 27, 2015, the GHOST vulnerability was announced by Qualys. This vulnerability allows remote attackers to take complete control of a system by exploiting a buffer overflow bug in a glibc function GetHOST. This vulnerability should be considered serious and all affected servers should be patched immediately.

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The GHOST vulnerability can be exploited on Linux systems that use versions of the GNU C Library prior to glibc-2.18. All Linux systems that use glibc from versions 2.2 to 2.17 are at risk. The following Linux distributions should be checked and patched:

• CentOS 6 & 7
• Debian 7
• Red Hat Enterprise Linux 6 & 7
• Ubuntu 10.04 & 12.04

Install Security Updates:
The easiest way to fix the GHOST vulnerability is to upgrade glibc to the latest version.

CentOS / RHEL
Update glibc to the latest version via yum:
# sudo yum update glibc

Respond to the confirmation prompt with y.

NOTE: When the update is complete, reboot the server:
# sudo reboot

Ubuntu / Debian
For  Ubuntu or Debian, update all of your system packages via apt-get dist-upgrade:
# sudo apt-get update && sudo apt-get dist-upgrade

Respond to the confirmation prompt with y.

NOTE: When the update is complete, reboot the server:
# sudo reboot