Ticket #50620: 50620.diff

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

@@ -54 +54 @@
                                                         'description'       => __( 'Attributes for the block' ),
                                                         'type'              => 'object',
                                                         'default'           => array(),
+                                                        'sanitize_callback' => static function ( $value, $request ) {
+                                                                $block = WP_Block_Type_Registry::get_instance()->get_registered( $request['name'] );
+
+                                                                if ( ! $block ) {
+                                                                        // This will get rejected in ::get_item().
+                                                                        return true;
+                                                                }
+
+                                                                $schema = array(
+                                                                        'type'                 => 'object',
+                                                                        'properties'           => $block->get_attributes(),
+                                                                        'additionalProperties' => false,
+                                                                );
+
+                                                                return rest_sanitize_value_from_schema( $value, $schema );
+                                                        },
                                                         'validate_callback' => static function ( $value, $request ) {
                                                                 $block = WP_Block_Type_Registry::get_instance()->get_registered( $request['name'] );