That's not really a problem with JSON though is it? Anything you run through eval() is a disaster in the making. Maybe the problem is that people are trying to make data formats too powerful, and too many things seem to be creeping towards Turing completeness that don't need to be.
I think parsers for JSON and Yaml, INI etc should be designed in such a way as to make it impossible to assign anything like an object, class, function, etc. Numbers, strings, and collections of numbers and strings... that's all you should get (though obviously "string" is frought with peril.) Anything more is unnecessarily complex.
