Often claimed as a worst-case scenario, a container breakout vulnerability has been discovered in RunC, the universal container runtime used by Docker, Kubernetes and other containerization systems.
Further research has discovered that a similar version of the same vulnerability affects the LXC and Apache Mesos packages. Identified as CVE-2019-5736, this vulnerability grants root access to host systems running all of the most popular containerization technologies.
A container breakout occurs when a malicious Docker image or container exploits a vulnerability in order to achieve a level of access on the host system. While extremely rare, it has been years since a container breakout vulnerability has been disclosed in a core component of Docker – that streak has now ended.
This vulnerability allows a container to overwrite the RunC binary and gain root level code execution access with minimal user interaction. This vulnerability can be exploited in the following ways:
Since a large portion of containers are based on images created by third-parties, it is vital to patch systems immediately as most users will have exposure to images and containers created by unknown parties.