CVE-2026-94603: Podman: The `podman run` command can be instructed to disable almost all sandboxing by image annotation

Podman v4.4.0 added a feature where container checkpoints (from the podman container checkpoint command) could be distributed via OCI registry, and pulled from that registry and run via the podman run command. This allowed easy transfer of checkpoints between systems. However, checkpoints allow complete control of how the container is created - including full control of the container sandbox. When podman run detects a checkpoint, it will silently ignore all user input regarding how the container should be created - for example, podman run --cap-drop=ALL on an image that is determined to be a checkpoint will ignore --cap-drop=all and use the set of capabilities specified by the checkpoint image instead, which could include all capabilities. Podman identifies checkpoint images by looking for an annotation, io.podman.annotations.checkpoint.runtime.name. If this annotation is set, the image is treated as a checkpoint. Conflating container images and checkpoints in podman run allows inherently insecure behavior as the image can now control how it is executed. The Podman Maintainers have determined that the safest course of action is to remove this functionality.