File extensions

With 3.x you could limit what file types could be uploaded, with 4.x you cannot.

I understand that an exe file is not a security concern for the server itself, but it might be if someone where to upload one and the user runs it.

I have one small site of active users that I trust, that site is running 4.x.  I will not upgrade my larger site that has thousands of users as it's not possible to know them all and trust them.  I won't expose some users to the potential of a security risk.

Please add this missing feature back.

Thank you