Is parsing JSON on the serverside dangerous?
You never know what the parser does inside. A parsing itself is a possible security threat, although the developers try to do their best to avoid it. 
For a stable library that's been developed for a long time, there's nearly no danger.
I'm writing a Python application with Django and serializing objects to and from JSON using Python's standard json library.
I've heard something along the lines that 

any seralizer/deserializer/parser is a potential security threat to the application

Is this really true on the serverside? Do I need to fear someone sending tampered JSON up to my instance and them having remote code execution privileges? I would think that there wouldn't be any security threats other than (potentially) XSS or SQL injection, which in my case (converting values to ints, storing all data in MongoDB) shouldn't be the case.
Should I be paranoid along these lines of parsing JSON data from clients?