diff --git src/wp-admin/includes/ajax-actions.php src/wp-admin/includes/ajax-actions.php
index c5718ae..28a7838 100644
--- src/wp-admin/includes/ajax-actions.php
+++ src/wp-admin/includes/ajax-actions.php
@@ -1855,7 +1855,7 @@ function wp_ajax_upload_attachment() {
 
 	if ( isset( $_REQUEST['post_id'] ) ) {
 		$post_id = $_REQUEST['post_id'];
-		if ( ! current_user_can( 'edit_post', $post_id ) ) {
+		if ( ! current_user_can( 'edit_posts', $post_id ) ) {
 			wp_send_json_error( array(
 				'message'  => __( "You don't have permission to attach files to this post." ),
 				'filename' => $_FILES['async-upload']['name'],