The Advanced Custom Fields: Extended WordPress plugin before 0.9.2.7 does not restrict the role submitted through its front-end user forms to the roles the form actually offers, and its safeguard against privileged roles is incomplete, allowing unauthenticated visitors to register an account with elevated capabilities and then escalate it to administrator.

The Advanced Custom Fields: Extended WordPress plugin before 0.9.2.7 does not verify that the requester is authorized to edit the targeted user account in the update-user action of its front-end Forms module; it only checks a capability when the submitted role is administrator or superadmin. On a site that exposes a publicly reachable front-end form whose user-update action targets an existing administrator (a fixed target, or one mapped to a visitor-submitted field) and maps the password to a visitor-submitted field, an unauthenticated visitor can overwrite that administrator's password and take over the account. The default target is the submitting user, so exploitation depends on the form being configured to target another account.

The Advanced Custom Fields (ACF®) plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 6.8.1. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to overwrite the posttitle and postcontent of any post bound to a publicly accessible acfform() instance by injecting values into the posttitle and postcontent parameters of a form submission request.

The Advanced Custom Fields (ACF) plugin for WordPress is vulnerable to Missing Authorization to Arbitrary Post/Page Disclosure in versions up to and including 6.7.0. This is due to AJAX field query endpoints accepting user-supplied filter parameters that override field-configured restrictions without proper authorization checks. This makes it possible for unauthenticated attackers with access to a frontend ACF form to enumerate and disclose information about draft/private posts, restricted post types, and other data that should be restricted by field configuration.

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Remote Code Execution in versions 0.9.0.5 through 0.9.1.1 via the prepareform() function. This is due to the function accepting user input and then passing that through calluserfuncarray(). This makes it possible for unauthenticated attackers to execute arbitrary code on the server, which can be leveraged to inject backdoors or create new administrative user accounts.

The Secure Custom Fields WordPress plugin before 6.3.9, Secure Custom Fields WordPress plugin before 6.3.6.3, Advanced Custom Fields Pro WordPress plugin before 6.3.9 does not prevent users from running arbitrary functions through its setting import functionalities, which could allow high privilege users such as admin to run arbitrary PHP functions.

In Advanced Custom Fields (ACF) before 6.3.9 and Secure Custom Fields before 6.3.6.3 (plugins for WordPress), using the Field Group editor to edit one of the plugin's fields can result in execution of a stored XSS payload. NOTE: if you wish to use the WP Engine alternative update mechanism for the free version of ACF, then you can follow the process shown at the advancedcustomfields.com blog URL within the References section below.