if you happen to receive an email similar to the one above, don't panic.
The bug bounty programs including the openbugbounty is a system designed to make the public accessible systems safe. Rather than a hacker misusing the exploit, bug bounty hackers warn you of a possible exploit, and give you enough time to fix it before they make this information public. Hence they are the good guys are you are not being threaten.
This is a great way forward, and big companies like Facebook, Google, run their own bug bounty program offering a huge reward for those who manage to find a genuine issue.
If you have received this, its very likely you have a vulnerability that can be exploited. You can review your logs to check what kind of activity or requests you have got the last few days to try to figure out the source of the issue. You can contact bug bounty program, and contact the hacker for more details, many of whom may give you the details of the exploit for a small fee or even for free. However its important to fix the issue as soon this exploit will be made public which means a malicious user can exploit it.
sapnasecurity has dealt with a couple of these and we are happy to help you explore and fix these incidents.