The ConvertPlus plugin for WordPress is vulnerable to unauthorized modification of data that can lead to a denial of service due to a missing capability check on the 'cp_dismiss_notice' AJAX endpoint in all versions up to, and including, 3.5.30. This makes it possible for authenticated attackers, with Subscriber-level access and above, to update option values to '1' on the WordPress site. This can be leveraged to update an option that would create an error on the site and deny service to legitimate users or be used to set some values to true such as registration.

The ConvertPlus plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 3.5.26 via deserialization of untrusted input from the 'settings_encoded' attribute of the 'smile_modal' shortcode. This makes it possible for authenticated attackers, with contributor-level access and above, to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

The ConvertPlus plugin before 3.4.5 for WordPress has an unintended account creation (with the none role) via a request for variants.