CVE-2026-103916: Docker Sandboxes sbx cp follows workspace symlinks outside the authorized host directory

Docker Sandboxes sbx cp does not safely confine host-side paths to a shared workspace. A malicious sandbox can create or replace a workspace symlink so that a later user-initiated copy reads a host file outside the workspace into the sandbox or writes sandbox-controlled data to a host path outside the workspace with the invoking user's permissions.