Excel file validation in laravel dose not work

try

$this->validate($request,
[
   'file'=> 'required|mimes:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
]);

https://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types

I tried validators provided by laravel but all doesnt seems to work.. That gave me an idea to try to validate using normal php and it works like a cham

$extensions = array("xls","xlsx","xlm","xla","xlc","xlt","xlw");

$result = array($request->file('import_file')->getClientOriginalExtension());

if(in_array($result[0],$extensions)){
     // Do something when Succeeded 
}else{
   // Do something when it fails
}

The issue with this solution is that an attacker could bypass your security by just changing the extension of the file. Mimes validation inspect the content of the file to make sure it is truly the desired type.