I suppose the first question that springs to mind is why would anybody want to alter the POST ID of the thread they're replying to?

Of course, if they wanted to post a nonsensical response in a random thread, they'd navigate to that thread and post. So as long as you're checking if they have permission to post in that thread, and the thread is valid, where does the problem arise? And what does the so-called master hacker achieve?

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