How many civilizations are known to have been wiped out by a CME?
This is 2020, normal does not apply. Everything is a civilization ending event.
A fair question, but difficult. Historically, civilizations have been wiped out by "natural events" plenty of times, and a few of those could have been CME related. But we don't know.
What we DO know is that a CME like the one that caused the Carrington Event (https://en.m.wikipedia.org/wiki/Carrington_Event) would almost certainly take out all the power grids, electronic equipment (computers, cell phones, automobiles, etc.), communications, etc. Airplanes and satellites would die and most would start falling out of the sky. Who knows what military gear would go haywire, and with what effects (it isn't all protected against CMEs). Modern life -- modern civilization -- would be vastly damaged and would take decades to recover to a recognizable industrial level.
You might argue that that is not the "end of civilization", and you would be right, except for one thing. Humans would freak out completely, and they would destroy what was left of civilization after the CME's destruction.