Published: 2 March 2022
containerd is a container runtime available as a daemon for Linux and Windows. A bug was found in containerd prior to versions 1.6.1, 1.5.10, and 1.14.12 where containers launched through containerd’s CRI implementation on Linux with a specially-crafted image configuration could gain access to read-only copies of arbitrary files and directories on the host. This may bypass any policy-based enforcement on container setup (including a Kubernetes Pod Security Policy) and expose potentially sensitive information. Kubernetes and crictl can both be configured to use containerd’s CRI implementation. This bug has been fixed in containerd 1.6.1, 1.5.10, and 1.4.12. Users should update to these versions to resolve the issue.
From the Ubuntu security team
It was discovered that containerd allows attackers to gain access to read-only copies of arbitrary files and directories on the host via a specially-crafted image configuration. An attacker could possibly use this issue to obtain sensitive information.
CVSS 3 base score: 7.5
While this was fixed in USN-5311-1, a subsequent SRU regressed the security update.