Security company, Qualys, has discovered a Linux [glibc vulnerability](https://community.qualys.com/blogs/laws-of- vulnerabilities/2015/01/27/the-ghost-vulnerability) that they have named “GHOST” (because it is a gethostbyname vulnerability) with a cute logo included as well. 
As it turns out, it is not that new. The first vulnerable version of the GNU C library is glibc-2.2. This exploit was fixed in between glibc-2.17 and glibc-2.18 on May 21, 2013. It was not classified as a security issue. This means that your stable or long-term distro is most likely affected (eg. RHEL 5, 6, 7, CentOS 6, 7, Ubuntu 12.04, Debian wheezy). My Ubuntu 14.04 LTS systems have been patched by Canonical.