diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php
index 94d75cf42a..bd0c920c0f 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php
@@ -664,6 +664,13 @@ class WP_REST_Comments_Controller extends WP_REST_Controller {
 			return $prepared_args;
 		}
 
+		if ( ! empty( $prepared_args['comment_post_ID'] ) ) {
+			$post = get_post( $prepared_args['comment_post_ID'] );
+			if ( empty( $post ) ) {
+				return new WP_Error( 'rest_comment_invalid_post_id', __( 'Invalid post ID.' ), array( 'status' => 403 ) );
+			}
+		}
+
 		if ( empty( $prepared_args ) && isset( $request['status'] ) ) {
 			// Only the comment status is being changed.
 			$change = $this->handle_status_param( $request['status'], $id );
@@ -690,7 +697,7 @@ class WP_REST_Comments_Controller extends WP_REST_Controller {
 
 			$updated = wp_update_comment( wp_slash( (array) $prepared_args ) );
 
-			if ( 0 === $updated ) {
+			if ( false === $updated ) {
 				return new WP_Error( 'rest_comment_failed_edit', __( 'Updating comment failed.' ), array( 'status' => 500 ) );
 			}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 4cf8134f11..00ef2f560e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7.1-alpha-39627';
+$wp_version = '4.7.1-alpha-39628';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.