We'll create fresh WordPress site with Pro Mime Types – Manage file media types installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Pro Mime Types adds a nifty (network) admin interface for allowing or blocking many file extensions for uploading media, documents, and other attachments.
It also shows you a list of all allowed MIME types on the site or network.
For WordPress Multisite networks, you can enable this plugin in network mode to control MIME types for the entire network.
This plugin can run in network mode, where all sites are allowed one set of MIME types. You can configure the allowed MIME types via the network administration UI.
Alternatively, Pro Mime Types can run in single-site mode, where every subsite has custom-allowed MIME types. Only the network administrator can assign these on a per-site basis.