JSON vs. Pickle security

I recently came across the security proble开发者_如何转开发ms of the Python pickle and cPickle modules. Obviously, there are no real security measures implemented in pickle unless you overwrite the find_class method as a basic modification to get a bit more security. But I often heard that JSON is more secure.

Can anyone elaborate a bit on this?`Why is JSON more secure than pickle?

Thanks a lot! Mark

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json is more secure because it's fundamentally more limited. The only python types that a json document can encode are unicode, int, float, NoneType, bool, list and dict. these are marshaled/unmarshalled in a basically trivial fashion that isn't vulnerable to code injection attacks.

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Pickle's problem is that it will can invoke arbitrary Python code. See http://nadiana.com/python-pickle-insecure for details. The JSON parser only has to create strings, numbers, lists, dicts, and so on. It never creates user-defined classes, so it doesn't need to execute arbitrary Python.