Quora says data breach affects 100 million users

The question-and-answer sharing website Quora says about 100 million users were affected by a hack blamed on a “malicious third party.”

We have discovered that some user data was compromised by unauthorized access to our systems. We’ve taken steps to ensure that the situation is contained and are notifying affected users. Protecting your information is our top priority. Read more here: https://t.co/uwbdMjoM1v
— Quora (@Quora) December 3, 2018

Account information that was accessed by this mysterious third party includes user name, email address, encrypted password, any data imported from linked networks like Facebook, per Quora in a statement today.
Reuters:

The company said it is logging out all Quora users who may have been affected to prevent further damage.
'We are in the process of notifying users whose data has been compromised,' Quora CEO Adam D'Angelo said in a blog post here
The breach, discovered on Friday, did not affect question and answers that are written anonymously, the company said, adding that it has also notified law enforcement officials.
“We have retained a leading digital forensics and security firm to assist us,” it said.
The Quora Inc-owned website was founded in 2009 by D’Angelo and Charlie Cheever, two former Facebook (FB.O) employees.