Doesn't Ubuntu have unprivileged userns available, just like e.g. Fedora? If so, then bwrap isn't setuid, and offers no more attack surface than the kernel does to every process (that doesn't have access to CLONE_NEWUSER denied via e.g. seccomp, as e.g. Docker does by default for its containers).
> bubblewrap is setuid
Doesn't Ubuntu have unprivileged userns available, just like e.g. Fedora? If so, then bwrap isn't setuid, and offers no more attack surface than the kernel does to every process (that doesn't have access to CLONE_NEWUSER denied via e.g. seccomp, as e.g. Docker does by default for its containers).