The Subscriptions & Memberships for PayPal plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.1.6. This is due to missing or incorrect nonce validation on a function. This makes it possible for unauthenticated attackers to delete arbitrary posts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://wordpress.org/plugins/subscriptions-memberships-for-paypal/#developers
https://plugins.trac.wordpress.org/changeset/3246039/subscriptions-memberships-for-paypal