A few months ago I noticed that even without `--dangerously-skip-permissions`, when Claude thought it was restricting itself to directory D, it was still happy to operate on file `D/../../../../etc/passwd`.
That was the last time I ran Claude Code outside of a Docker container.
You don't even need a container. Make claude a local user. Without sudo permission. It will be confined to damaging its own home directory only.
By operate on you mean that actually got through and it opened the file?
It will happily run bash commands, which expands it's reach pretty widely. It's not limited to file operations, and can run system wide commands with your user permissions.