Hello,
Our theme code doesn’t have any vulnerabilities.
Concerning security you can contact your hosting provider support.
Also read these articles:
https://www.siteground.com/tutorials/wordpress/wordpress_security.htm
https://hostingfacts.com/how-to-secure-wordpress/
https://www.sitepoint.com/tips-to-secure-wordpress/
As for contact form, as I see you’re using Contact Form 7 plugin, then refer to this article how to add Captcha:
http://contactform7.com/recaptcha/
Regards,
Eva Kemp.