If you are using Python - assuming there are no exploits in the http, requests and json lib - you'd have to really do something unusual to execute code that's inside the response.
Code injection can be used for attacks, so I thought I'd mention it at least. Not really a big concern, though. With javascript I'd maybe be a little more worried.
And finally you could use it to inject code to a server of yours. Remote control stuff by chain upload... Probably useless, but cool.