Worst case they proxy all of the requests and can essentially access anything open on the port. For me it's all development stuff, so if they want access to a b

Worst case they proxy all of the requests and can essentially access anything open on the port. For me it's all development stuff, so if they want access to a broken-half-the-time application with mock data then whatever. However they'd have to know the routes to request to (or proxy all requests and do it in realtime) which isn't very likely if it's just some development application specific to you. Basically there really isn't much risk if you aren't exposing anything interesting. Maybe if you're working on something proprietary it could be leaked? Either way you may as well reconfigure your applications if the webpage can detect them, the risk is low but still existent.