Well, it is always possible that attacker broke out of the container, as the container is still running under the same kernel, only its process(es) are chrooted

Well, it is always possible that attacker broke out of the container, as the container is still running under the same kernel, only its process(es) are chrooted + namespaced. Containerized "root" supposedly has its' privileges cut down, but if the kernel is exploitable...