Software dev perspective: While this could've been reported better (more details, less public), the responses are leaning too closely to the "don't report bugs" side of the spectrum for comfort. I'm seeing no malicious intent on failure_supreme's part (and the alt accounts thing doesn't seem relevant? or did I miss a discussion somewhere?), and we really ought not be discouraging folks to find/report bugs. That just builds a culture in which exploits happen often and nobody reports them for fear of punishment.
Related: asking puke "Hey, does bug 'x' exist?" isn't a viable alternative to trying a thing because then he not only has to test it himself (or just assume it works without testing, which is how bugs proliferate in the first place), but also because it wastes his time in the case where things are A-OK (no bug).
The flipside: Adding extra bug details (e.g. "I made a manual POST request and it let me do 'y'") or theories (e.g. "I would guess the problem is 'z'") is exceptionally useful to dev-folk and not at all insulting... well, unless there's an actual insult in there ("oh my GOD i cannot BELIEVE this is broken, how do you let this happen you nincomflarp"). Vagueness isn't helpful.
Related idea: It might be worth adding some sort of note somewhere to report any security/exploit-related things to puke privately, or else build a private-submit system where only admins can read the messages, but that'd require coding effort.
Thought-dump: concludes.