The 404 to 301 plugin for WordPress is vulnerable to authorization bypass due to missing capability checks on the open_redirect & save_redirect functions in versions up to, and including, 3.0.7. This makes it possible for authenticated attackers to view, create and edit redirections.
https://wpscan.com/vulnerability/9f147107-bc5a-4a01-9979-cd9e16061f12
https://plugins.trac.wordpress.org/changeset/2546695/404-to-301