How could he have known on Oct 17 that it was about to be disclosed? The dates only leaked on Oct 20.

You're asking: How could a hacker - with an exploit that potentially allows him/her to break into half the computers on the internet - know some secret information that is stored on a computer on the internet?

It could also just have been a run-of-the-mill exploit in WordPress.

	▲	cubefox 17 minutes ago \| parent [-]
		A leak is a much simpler explanation than an independent discovery who then also managed to discover before publication that someone else has also discovered it.