diff --git a/src/wp-includes/rest-api.php b/src/wp-includes/rest-api.php
index 620ca925b9..6da931e77a 100644
--- a/src/wp-includes/rest-api.php
+++ b/src/wp-includes/rest-api.php
@@ -408,6 +408,7 @@ function rest_send_cors_headers( $value ) {
 		header( 'Access-Control-Allow-Origin: ' . esc_url_raw( $origin ) );
 		header( 'Access-Control-Allow-Methods: POST, GET, OPTIONS, PUT, DELETE' );
 		header( 'Access-Control-Allow-Credentials: true' );
+		header( 'Vary: Origin' );
 	}
 
 	return $value;