diff --git a/.env.example b/.env.example
index 77e6c80..38f63cb 100644
--- a/.env.example
+++ b/.env.example
@@ -32,3 +32,4 @@ MERCURE_PUBLIC_URL=https://example.com/.well-known/mercure
 # The secret used to sign the JWTs
 MERCURE_JWT_SECRET="!ChangeThisMercureHubJWTSecretKey!"
 ###< symfony/mercure-bundle ###
+CORS_ALLOW_ORIGIN='^https?://(localhost|127\.0\.0\.1)(:[0-9]+)?$'