wpninjas/ninja-forms — pull request #333 by robneu (2014-10-01 15:34:26+00:00)
Title: Hide submissions from the front-end

Right now anyone who knows what URL structure to look for or what query
string to use can pull submission information on the front end. This
should fix the issue.

I’m not sure what other ramifications there might be from changing this
setting because I’m not all that familiar with the plugin; however,
this is definitely something that should be fixed.