containerd CRI stream server vulnerable to host memory exhaustion via terminal

Impact

A bug was found in containerd's CRI implementation where a user can exhaust memory on the host. In the CRI stream server, a goroutine is launched to handle terminal resize events if a TTY is requested. If the user's process fails to launch due to, for example, a faulty command, the goroutine will be stuck waiting to send without a receiver, resulting in a memory leak. Kubernetes and crictl can both be configured to use containerd's CRI implementation and the stream server is used for handling container IO.

Patches

This bug has been fixed in containerd 1.6.12 and 1.5.16. Users should update to these versions to resolve the issue.

Workarounds

Ensure that only trusted images and commands are used and that only trusted users have permissions to execute commands in running containers.

For more information

If you have any questions or comments about this advisory:

• Open an issue in containerd
• Email us at [email protected]

To report a security issue in containerd:

• Report a new vulnerability
• Email us at [email protected]