after entering in last level, you need to change the shell.

:set shell=/bin/bash

and then, call the shell

:shell

bandit26@bandit:~$ ./bandit27-do cat /etc/bandit_pass/bandit27
upsNCc7vzaRDx6oZC6GiR6ERwe1MowGB

Flag: upsNCc7vzaRDx6oZC6GiR6ERwe1MowGB