Advanced Custom Fields: Extended vulnerabilities

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. This allows 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 super_admin. On a site that exposes a publicly reachable front-end form whose user-update action targets an existing administrator 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 plugin for WordPress up to version 0.9.2.5 is vulnerable to privilege escalation via validation bypass. The after_validate_save_post() function unconditionally trusts the attacker-controlled _acf_post_id parameter, allowing validation errors to be suppressed and an administrator account to be created.