Ticket #40861: 40861.2.patch

src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

@@ -136 +136 @@
                 }
 
                 $attachment                 = $this->prepare_item_for_database( $request );
-                $attachment->file           = $file;
                 $attachment->post_mime_type = $type;
                 $attachment->guid           = $url;
 
@@ -144 +143 @@
                         $attachment->post_title = preg_replace( '/\.[^.]+$/', '', basename( $file ) );
                 }
 
-                $id = wp_insert_post( wp_slash( (array) $attachment ), true );
+                // $post_parent is inherited from $attachment['post_parent'].
+                $id = wp_insert_attachment( wp_slash( (array) $attachment ), $file, 0, true );
 
                 if ( is_wp_error( $id ) ) {
                         if ( 'db_update_error' === $id->get_error_code() ) {