Information on old bitcoin inflation bug

[bigmelons25]

I was watching a video by Richard Heart ( crypto youtuber that was around during early btc days) and he briefly touched upon that latest bitcoin inflation bug that happened to be discovered by a bitcoin cash developer before it was too late.  He didn't really go heavy into detail but I would like to get some more information about this near catastrophic event from knowledgeable users.  I really haven't been able to find much information through various search avenues.

[achow101]

The full disclosure write up for the vulnerability can be found here: https://bitcoincore.org/en/2018/09/20/notice/