diff --git a/wp-includes/rest-api/class-wp-rest-request.php b/wp-includes/rest-api/class-wp-rest-request.php
index 23156a31b0..d3e8c755af 100644
--- a/wp-includes/rest-api/class-wp-rest-request.php
+++ b/wp-includes/rest-api/class-wp-rest-request.php
@@ -804,6 +804,11 @@ class WP_REST_Request implements ArrayAccess {
 				continue;
 			}
 			foreach ( $this->params[ $type ] as $key => $value ) {
+				// if no sanitize_callback was specified, default to rest_parse_request_arg
+				// if a type was specified in the args.
+				if ( ! isset( $attributes['args'][ $key ]['sanitize_callback'] ) && ! empty( $attributes['args'][ $key ]['type'] ) ) {
+					$attributes['args'][ $key ]['sanitize_callback'] = 'rest_parse_request_arg';
+				}
 				// Check if this param has a sanitize_callback added.
 				if ( ! isset( $attributes['args'][ $key ] ) || empty( $attributes['args'][ $key ]['sanitize_callback'] ) ) {
 					continue;
diff --git a/wp-includes/version.php b/wp-includes/version.php
index a1c841520f..ec36fca073 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta1-39090';
+$wp_version = '4.7-beta1-39091';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.