Bugs n stuff?

I always hear of bugs like duping items, or money and stuff like that. but i hear about them after they get patched. so what im saying is, is there like a website where the exploits are posted before they get patched?

 

Most of them are private/sold

 

Not really.....
Most of the time you need to be smart/lucky to find one.
Once you do you abuse the shit out of it an keep it private as best you can.
The second it leaks it leaks fast, gets patched fast, and becomes useless.
No one is stupid enough to post/leak their methods (on purpose).

Only way is to find your own or be told by someone or catch the last few hours of a leaked method.