CVE-2026-3309: Paid Membership Plugin, Ecommerce, User Registration Form, Login Form, User Profile & Restrict Content – ProfilePress <= 4.16.11 - Unauthenticated Arbitrary Shortcode Execution via Checkout Billing Fields

The Paid Membership Plugin, Ecommerce, User Registration Form, Login Form, User Profile & Restrict Content – ProfilePress plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 4.16.11. This is due to the plugin allowing user-supplied billing field values from the checkout process to be interpolated into shortcode template strings that are subsequently processed without proper sanitization of shortcode syntax. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes by submitting crafted billing field values during the checkout process.