Advanced Custom Fields: Extended <= 0.9.2.6 - Missing Authorization to Unauthenticated Arbitrary Attachment Deletion via Email Action Dynamic File Field

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.