Perhaps you're right. But "Facebook report a vulnerability" works just fine and that's what I would have tried if I were trying to report a vulnerability.
It looks like the magic search term that brings you right to the report page is: "Facebook vulnerability"
http://google.com/?q=Facebook+vulnerability
Perhaps you're right. But "Facebook report a vulnerability" works just fine and that's what I would have tried if I were trying to report a vulnerability.