Release Date 10th September 2026
- Security - ACF now validates that uploaded PDF files begin with the standard
%PDF-header before further processing, rejecting files that do not match the expected format - Security - The Relationship, Post Object, Image, Gallery, and File fields now enforce WordPress read permissions on referenced posts and attachments when returned in REST API responses
- Security - ACF now verifies both preview context and the caller's edit capability before substituting revision data when field values are retrieved for a post
- Security - The
_acf_formtoken used by frontend forms now expires and is bound to its issuing render, andacf_encrypt()/acf_decrypt()gain an optional$contextargument for domain separation between token uses - Security - ACF now consistently runs field validation on frontend form submissions containing field data, ensuring required-field checks and custom
acf/validate_valuefilters cannot be circumvented - Security - ACF's REST API schema no longer discloses per-object field-group configuration in OPTIONS requests to callers who lack read permission on the target object
- Security - The User field AJAX endpoint now validates that the request nonce was created for a User field