Estatik Real Estate Plugin < 4.3.3 - Unauthenticated Arbitrary-Recipient Mail Relay via Request Form

The Estatik Real Estate Plugin WordPress plugin before 4.3.3 does not properly enforce its anti-spam check or restrict the recipient routing of its property request form, allowing unauthenticated users to send emails to arbitrary recipients with arbitrary subject, body and Reply-To, effectively using the site as a mail relay for spam or phishing.