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 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: 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 (ACF®) WordPress plugin before 6.8.11 does not properly sanitize a stored field definition that can be modified through its comment handling, allowing unauthenticated users to inject a payload that is emitted as an HTML attribute name and executed as JavaScript in the browser of any visitor or administrator who views a page rendering the affected field.

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.

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 (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: Extended plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 0.9.2.6. 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 permanently delete arbitrary WordPress media library attachments by supplying a numeric attachment ID in the form submission without any ownership or capability verification. Exploitation requires a site administrator to have configured a public-facing ACFE form with an Email action whose attachment row uses a dynamic {field:...} source bound to a submittable field with the Delete option enabled.

The Advanced Custom Fields (ACF®) WordPress plugin before 6.8.11 does not verify that a user is allowed to edit the target object before writing to it during bidirectional relationship synchronization, allowing users with contributor-level access and above to add or remove a reference to their own object on arbitrary posts, users, or terms they cannot otherwise edit.

The Advanced Custom Fields (ACF®) WordPress plugin before 6.8.11 does not perform a read-permission check when it renders and formats the values of its relational fields, allowing users with post-editing access (Contributor and above) to disclose the titles and non-public statuses of other users' unpublished posts.

The Advanced Custom Fields (ACF®) WordPress plugin before 6.8.11 does not re-apply its field-group location rules when persisting values submitted through the post editor save path, allowing users with contributor-level access and above to write custom fields the site restricted to administrators onto their own posts.