Impact

A vulnerability in containerd's CRI implementation allows a container restored from an untrusted checkpoint via the CreateContainer API to bypass the destination security context and execute with elevated privileges. When restoring a container from a checkpoint archive or annotated OCI image, CRIU restores process credentials, Linux capabilities, nonewprivs, and seccomp state directly from checkpoint data rather than enforcing the destination CRI ContainerConfig. An attacker who can run a container with a crafted checkpoint image can execute processes as root with full capabilities and no enforced seccomp filters despite restrictive security policies requested by the orchestrator. Additionally, containerd's CRI status reporting reflects the requested configuration rather than the actual restored process state, masking the privilege discrepancy from orchestrators. This issue affects Linux systems running containerd with CRI checkpoint restore enabled; users not utilizing CRI checkpoint restore are not affected.

Patches

This bug has been addressed in containerd 2.2.7 and 2.3.4 by disabling checkpoint restore via CreateContainer by default. The feature has been removed entirely in containerd 2.4.0. Users should update to these versions to resolve the issue. Running containers that were restored from untrusted checkpoints should be stopped, deleted, and recreated.

Users who rely on restore via the CreateContainer API can re-enable the feature by setting the new enableexperimentalrestoreviacreate configuration option. However, enabling restore via CreateContainer leaves this vulnerability present, as containerd cannot enforce destination security policy during CRIU process restoration.

Workarounds

On unpatched versions, containerd does not provide a configuration option to disable checkpoint restore via CreateContainer. Deployments should restrict container creation permissions to trusted users, validate container image registries, or use admission controllers to reject images containing checkpoint data.

References

CRIU image security

Credits

The containerd project would like to thank @l2yyd5 and @berkpolatCE for responsibly disclosing this issue in accordance with the containerd security policy.

For more information

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