The Contact Form by Supsystic WordPress plugin before 1.11.1 does not verify a CSRF nonce before saving its mail settings, allowing an attacker to overwrite the site's outbound mail configuration, including the SMTP server, its credentials and the notification recipient, by tricking a logged-in administrator into visiting a crafted page, which can route the Contact Form by Supsystic WordPress plugin before 1.11.1's contact-form notifications through infrastructure the attacker controls.
https://wpscan.com/vulnerability/102bbaf2-12c8-48b9-bacb-28de2baec45b/