One of the core issues here was a serialization library that was too convenient, with the ability to deserialize into arbitrary classes and end up executing code from them. In the Python world, this vulnerability has been a bit better known for a while (which is not to say that they are immune, but it's at least been common community knowledge for a very long time now, at least a decade). Pickle is well-known to have it, but it's frequently pointed out in the docs that it is possible and that you shouldn't unpickle things from users. But other libraries may have this too, and if Django uses them, have a poke around. JSON libraries would be one obvious point. There's probably some extant Perl vulnerabilities in this area too. PHP wouldn't surprise me (though it would be a particular framework and probably not the language as a whole).