Topic on Manual talk:Edit.php

"If the specified user does not exist, it will be created."

Is there a default password used for these created accounts? By default, could a person utilize these accounts for logging into the wiki? If I don't want these accounts to be abused, would I need to add them to $wgReservedUsernames?

The user created is initialized with a "not set" password, which means nobody can log in with that user account.