Security Researcher Harsha Vardhan Boppana found a Vulnerability in facebook which allows us to lock accounts in facebook. But facebook did not consider that vulnerability, as Minor amount of accounts were vulnerable to this.
According to researcher, daily we can lock some 1-2 accounts and also personal info can be retreived from those Lock accounts. He provide the demonstration of this attack.
A quick Google search can reveal the vulnerable accounts. Researcher used a Google dork "inurl:www.facebook.com/hacked/disavow". As this dork will display lot of search results, we can modify the dork by adding some date and list the recent accounts, "inurl:www.facebook.com/hacked/disavow september 19".
If we try this, Daily atleast 1-2 accounts will be prone to this attack. Researcher also tested this attack on some account and got success.
If u click 'This wasnt me', then the account will be locked. Using the link , we can get Network details and sometimes Device details. Also we can get some personal info.