There is an open redirect in the PhastPress WordPress plugin before 1.111 that allows an attacker to malform a request to a page with the plugin and then redirect the victim to a malicious page. There is also a support comment from another user one year ago (https://wordpress.org/support/topic/phast-php-used-for-remote-fetch/) that says that the php involved in the request only go to whitelisted pages but it's possible to redirect the victim to any domain.