You can restrict uploading media Files by Extensions and Types by editing the security policy file:

The security policy file (default.config, admin.config and guest.config) can be found in the /CuteEditor/Configuration/Security folder. In security policy file you can find the MediaFilters element element . By default, it contains the following value:

<security name="MediaFilters">

       <item>.mpg</item>
       <item>.avi</item>
       <item>.mp3</item>

</security>