If you are running Linux and a service or program returns the error:
cannot execute /bin/bash: Permission Denied
Or if your users are being logged off as soon as they log in, it’s not a big deal. For me, the fix was setting the suid bit on /bin/login using this command:
chmod 4755 /bin/login
I’ve read the error can also be caused by insufficient permissions in the /lib directory. As well, it could be insufficient permissions on / or /bin. I also had that once. / and /bin should both be set to 755.