Ubuntu 14.04 will be discontinued on April 30. Ubuntu 12.04 stopped receiving support 4 years and 11 months ago. Or well, this is the theory, because the version released in April 2012 received support this week. We are talking about a Linux kernel update for both versions, both LTS or Long Term Support, which corrects a security flaw of those that are not very dangerous but it is better not to have them in any operating system.
Linux Kernel 3.13, the one used by both Ubuntu v14.04 and v12.04, includes a bug that allows a malicious user to run programs as an administrator. What I think is the most important to mention is that in order for said user to be able to exploit the vulnerability, they have to have physical access to the computer so, at first, it is not too dangerous.
New version of Linux Kernel 3.13 fixes minor problem
The affected systems are all official Ubuntu systems and all those based on Canonical's operating system that have not fixed the bug on their own. It is certain that Ubuntu 14.04, Kubuntu 14.04, Lubuntu 14.04, Xubuntu 14.04 and Ubuntu Studio 14.04 are affected. Other official flavors, such as Ubuntu MATE or Ubuntu Budgie could be released, most notably a Budgie version that was first released in October 2015 (Budgie Remix 15.10). Ubuntu MATE should be affected, since its first version was precisely Ubuntu MATE 14.04, a release that was not LTS.
On the other hand and as we have mentioned previously, this update is also available for Ubuntu 12.04 ESM, who has received v3.13.0-166.216 ~ precise1. The version available for Ubuntu 14.04 is the same, but only the part with numbers.
Ubuntu 14.04 will stop receiving official support in about six weeks. From that moment on it is assumed that neither applications nor system will receive updates, so it is likely that users who remain in that version will be exposed to future threats. I am not saying that it is safe from the fact that Ubuntu 12.04 has received a kernel update 7 years after its release.
Canonical recommends updating all users who are on the versions mentioned in this article as soon as possible.