The GHOST vulnerability is a serious weakness in the Linux "glibc library". It allows attackers to remotely take complete control of the victim system.

GHOST is a 'buffer overflow' vulnerability 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 first vulnerable version of the GNU C Library affected by this vulnerability is glibc-2.2, released on November 10, 2000. The vulnerability was fixed on May 21, 2013 (between the releases of glibc-2.17 and glibc-2.18). Unfortunately, it was not recognized as a security threat; as a result, most stable and long-term-support distributions were left exposed.