Quora Inc is a question and answer website founded by former Facebook folks Charlie Cheever and Adam D’Angelo. 

CEO, Adam D’Angelo announced on Friday, November 30, 2018, that apparently an unauthorized access was discovered as having been conducted by a malicious 3^rd party.  User account names, email addresses, encrypted passwords, and network links were supposedly compromised. 

The investigation is still in progress.  Remedial steps being taken include disclosure notification emails, forced password resets, and users being forcefully logged out.