Yes, in Bitcoin's infancy (in 2010) a hacker created
92 184 billion Bitcoins using an exploit.
This is the thread about this legendary event.This is the only event I remember which was intentional and dangerous at the same time but Bitcoin wasn't worth (almost) anything then. Just 3 months earlier the
legendary pizza transaction had taken place.
In 2016 and 2017 there were also "stress tests" that were probably simply spam attacks, but all they reached was a congestion of the network.
Interesting story which I was unaware of. I thought that bitcoin is not hackable as I have been reading many different webpages outside of this forum that says bitcoin is protected by the laws of universe and math. I hope this never happens again especially now in our time as this would be very dangerous for the existence of bitcoin itself.