Incorrect Authorization in containerd/containerd

Summary

Containerd is an open source container runtime. A bug was found in containerd prior to versions 1.5.18,1.6.x prior to 1.6.18 and v1.7.x prior to v1.7.0-beta.4 where supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to Bypass primary group restrictions in some cases, potentially gaining access to Sensitive Information or gaining the ability to Execute Code in that container. Downstream applications that use the containerd client library may be affected as well. Users should update to these versions and recreate containers to resolve this issue. Users who rely on a downstream application that uses containerd's client library should check that application for a separate advisory and instructions. As a workaround, ensure that the "USER $USERNAME" Dockerfile instruction is not used. Instead, set the container entrypoint to a value similar to "ENTRYPOINT ["su", "-", "user"]" to allow "su" to properly set up supplementary groups.