How Rare Is It for Patched Vulnerabilities?

This is very rare. Like its super rare when you actually get the actual code for zero day dropped. Even, i would say it's even pretty rare for a patched vulnerability to have the actual source code of the vulnerability dropped. In this case, in this case, apple is very controllingof this kind of stuff. The bag bounty programme, which the researcher was been part of. He was hoping fora rabouny, and was going through the back bouny process. I believe that their conditions is that the researcher wo reports a bug, has to agree that they cannot write anything about the bug before apple tells them that it's ok to do it. Other times, researchers believe that