Rapid7 Vulnerability & Exploit Database

Docker cgroups Container Escape

Back to Search

Docker cgroups Container Escape



This exploit module takes advantage of a Docker image which has either the privileged flag, or SYS_ADMIN Linux capability. If the host kernel is vulnerable, its possible to escape the Docker image and achieve root on the host operating system. A vulnerability was found in the Linux kernel's cgroup_release_agent_write in the kernel/cgroup/cgroup-v1.c function. This flaw, under certain circumstances, allows the use of the cgroups v1 release_agent feature to escalate privileges and bypass the namespace isolation unexpectedly. More simply put, cgroups v1 has a feature called release_agent that runs a program when a process in the cgroup terminates. If notify_on_release is enabled, the kernel runs the release_agent binary as root. By editing the release_agent file, an attacker can execute their own binary with elevated privileges, taking control of the system. However, the release_agent file is owned by root, so only a user with root access can modify it.


  • h00die
  • Yiqi Sun
  • Kevin Wang
  • T1erno




Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':

msf > use exploit/linux/local/docker_cgroup_escape
msf exploit(docker_cgroup_escape) > show targets
msf exploit(docker_cgroup_escape) > set TARGET < target-id >
msf exploit(docker_cgroup_escape) > show options
    ...show and set options...
msf exploit(docker_cgroup_escape) > exploit

Time is precious, so I don’t want to do something manually that I can automate. Leveraging the Metasploit Framework when automating any task keeps us from having to re-create the wheel as we can use the existing libraries and focus our efforts where it matters.

– Jim O’Gorman | President, Offensive Security