Is parsing JSON on the serverside dangerous?
Yes. You should be paranoid. Just because the parsers are trusted does't mean you can't screw up.
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?