Docker Sandboxes privilege escalation through untrusted state directories

Docker Sandboxes reuses existing state and configuration directories without verifying their ownership. If sbx or sandboxd is run as root with HOME or, on Linux, XDG_STATE_HOME pointing to an attacker-controlled location, a local unprivileged user can substitute control-plane sockets and configuration trusted by the root process, potentially executing commands as root. Exploitation requires a privileged invocation with an attacker-influenced environment. The issue affects Linux and macOS and is fixed in version 0.53.0.