But I'd encourage you to do a bit more investigation.
According to Bitcoin core, there is an inflation vulnerability.
https://bitcoincore.org/en/2018/09/20/notice/
So maybe you weren't too far off from independently discovering the vulnerability yourself.
Edit: apparently you were credited in discovering the vulnerability yourself in the very discloser that I linked.
Congrats!
My comment was an early disclosure before I fully understood how sensitive the details were. Even without going into detail or providing any code it was very irresponsible of me to off hand just mention that possibility. It didn't click how sensitive things were until a bitcoin core dev confirmed it. Sorry anyone who sees this. I merely reported the exploit, David Jaenson is our genius security researcher that definitely should deserve all credit.