The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Privilege Escalation via Validation Bypass in all versions up to and including 0.9.2.5. The vulnerability exists due to the after_validate_save_post() function unconditionally trusting the attacker-controlled _acf_post_id POST parameter — with no authentication or integrity verification — to select a cleanup branch that silently discards all validation errors not prefixed with acfe:. This makes it possible for unauthenticated attackers to suppress both the role allow-list validation error added by acfe_field_user_roles::validate_front_value() and the administrator-role capability guard error added by acfe_module_form_action_user::validate_action(), causing wp_insert_user() to execute with an attacker-supplied administrator role argument and resulting in the creation of a new administrator-level user account. Exploitation requires the target site to expose a public ACFE frontend form configured with a Create User action that maps a role field.

The The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 0.9.2.3. 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 unauthenticated attackers to execute arbitrary shortcodes.

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 0.9.2.1. This is due to the 'insert_user' function not restricting the roles with which a user can register. This makes it possible for unauthenticated attackers to supply the 'administrator' role during registration and gain administrator access to the site. Note: The vulnerability can only be exploited if 'role' is mapped to the custom field.

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 prepare_form() function. This is due to the function accepting user input and then passing that through call_user_func_array(). 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 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'acfe_form' shortcode in versions up to, and including, 0.8.9.3 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

The Advanced Custom Fields: Extended WordPress plugin before 0.8.8.7 does not validate the order and orderby parameters before using them in a SQL statement, leading to a SQL Injection issue