The 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, 4.16.19. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for authenticated attackers, with subscriber-level access and above, to execute arbitrary shortcodes. The partial mitigation introduced via strip_shortcodes() on [profile-first-name] and [profile-last-name] can be bypassed through the [profile-display-name format="first_last_names"] render path, the [profile-bio] render path (which re-fetches the raw description meta), and the double-bracket escape sequence [[tag]], all of which allow attacker-controlled shortcode text to reach the outer do_shortcode() call.
Analyzing vulnerability vectors…