file upload validate

In a form made by Contact Form 7 I allow the download of a pdf, jpg, or jpeg file type. My concern is that the extension control is not fully performed.

Indeed, if I take a “test.exe” file and rename it “text.jpg”, I can submit my form and there’s no errors…

Is there a solution to test this? (e.g. by the mime test)

And if so where should I implement code?

Thank you in advance