If the container is running in privileged mode you can just talk to the docker socket to the daemon on the host, spawn a new container with direct access to the root filesystem, and then change anything you want as root.
Notably, if you run docker-in-docker, Docker is probably not a security boundary. Try this inside any dind container (especially devcontainers): docker run -it --rm --pid=host --privileged -v /:/mnt alpine sh
I disagree with other commenters here that Docker is not a security boundary. It's a fine one, as long as you don't disable the boundary, which is as easy as running a container with `--privileged`. I wrote about secure alternatives for devcontainers here: https://cgamesplay.com/recipes/devcontainers/#docker-in-devc...
Notably, if you run docker-in-docker, Docker is probably not a security boundary. Try this inside any dind container (especially devcontainers): docker run -it --rm --pid=host --privileged -v /:/mnt alpine sh
I disagree with other commenters here that Docker is not a security boundary. It's a fine one, as long as you don't disable the boundary, which is as easy as running a container with `--privileged`. I wrote about secure alternatives for devcontainers here: https://cgamesplay.com/recipes/devcontainers/#docker-in-devc...