Index: src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php
===================================================================
--- src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php	(revision 39302)
+++ src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php	(working copy)
@@ -366,11 +366,28 @@
 	 * @return WP_Error|bool True if the request has access to create items, error object otherwise.
 	 */
 	public function create_item_permissions_check( $request ) {
-
 		if ( ! is_user_logged_in() && get_option( 'comment_registration' ) ) {
 			return new WP_Error( 'rest_comment_login_required', __( 'Sorry, you must be logged in to comment.' ), array( 'status' => 401 ) );
 		}
 
+		/**
+		 * Filters whether comments can be created without authentication.
+		 *
+		 * Enables creating comments for anonymous users.
+		 *
+		 * @since 4.7.0
+		 *
+		 * @param bool            $allow_anonymous Whether to allow anonymous
+		 *                                         comments to be created.
+		 *                                         Default `false`.
+		 * @param WP_REST_Request $request         Request used to generate the
+		 *                                         response.
+		 */
+		$allow_anonymous = apply_filters( 'rest_allow_anonymous_comments', false, $request );
+		if ( ! is_user_logged_in() && false === $allow_anonymous ) {
+			return new WP_Error( 'rest_comment_login_required', __( 'Sorry, you must be logged in to comment.' ), array( 'status' => 401 ) );
+		}
+
 		// Limit who can set comment `author`, `author_ip` or `status` to anything other than the default.
 		if ( isset( $request['author'] ) && get_current_user_id() !== $request['author'] && ! current_user_can( 'moderate_comments' ) ) {
 			/* translators: %s: request parameter */