The MemberHero WordPress plugin through 6.9 does not perform any capability or nonce check on one of its AJAX actions, allowing any authenticated user, such as a subscriber, to make the site send arbitrary HTML emails to arbitrary recipients from its own mail system, which can be abused to relay phishing carrying the site's identity and domain reputation.

The MemberHero WordPress plugin through 6.9 does not perform any capability or nonce check on one of its AJAX actions, allowing any authenticated user, such as a subscriber, to make the site send arbitrary HTML emails to arbitrary recipients from its own mail system, which can be abused to relay phishing carrying the site's identity and domain reputation.