I've tried it and when I have the /graphql endpoint secured, then calling it over a websocket is possible without providing an auth header, because the websocket handler is placed before the authorization checks.

It seems to be exploitable only when you don't specify any role-based permissions (@RolesAllowed) on the GraphQL operation, because if you do, then Quarkus attempts to check the role of the user, which fails  with a NullPointerException (because the security identity is null and  Quarkus tries to check whether it has a role). When the policy says just that the user has to be authenticated, the request goes through. If there's any checking of the user metadata, the request fails with NPE. But all in all, it looks pretty bad to me, because websockets are always enabled (maybe we should also add an option to disable them)