Information
The PermitEmptyPasswords parameter specifies if the SSH server allows login to accounts with empty password strings.
Disallowing remote shell access to accounts that have an empty password reduces the probability of unauthorized access to the system.
Solution
Edit the /etc/ssh/sshd_config file to set the parameter above any Include entries as follows:
PermitEmptyPasswords no
Note: First occurrence of a option takes precedence, Match set statements withstanding. If Include locations are enabled, used, and order of precedence is understood in your environment, the entry may be created in a file in Include location.