Yesterday two issues affecting CPUs have been released to the public.
TL;DR: the attacks are named Meltdown and Spectre. They allow reading the memory of the OS or of other processes, to steal secrets or get information for other exploits. A part of the solution can greatly affect performance of running code. In particular, this attack allows to easily cross container boundaries, and in some cases (not our case) even VM boundaries.
In addition to servers, consumer machines are affected, especially through browsers, so you should definitely update your operating system as well as your browsers.