Notifying users whose data has been compromised, Quora said, "Out of an abundance of caution, we are logging out all Quora users who may have been affected, and, if they use a password as their authentication method, we are invalidating their passwords". In June 2016, hacking group OurMine broke into Google CEO Sundar Pichai's Quora account.
The company is now in the process of logging out and invalidating users who may have been affected.
It also includes content like posted questions, answers, comments and upvotes - which is public anyway - as well as answer requests, downvotes and direct messages. The company insists that only a low percentage of Quora users have sent or received such messages.
Marriott hotels also revealed on Friday that the FBI was investigating a data breach of its systems which exposed the details of up to 500 million guests.
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After launching at 11.31am GMT the three are set to dock at the International Space Station at exactly 5.36pm GMT. A Russian investigation attributed the failure to a sensor that was damaged during the rocket's final assembly.
"For approximately 100 million Quora users, the following information may have been compromised", D'Angelo wrote. It was also said that the root problem has been identified, and that the company has "taken steps to address the issue".
Quora said, in a statement emailed to members, that they are now investigating exactly how the breach occurred. Along with this, it is also asking the users to change their account passwords. Those wishing to delete their account can do so in the settings section and the deactivation will happen immediately.
Quora relies on the website traffic that comes from people searching questions in their browsers. "While the investigation is still ongoing, we have already taken steps to contain the incident, and our efforts to protect our users and prevent this type of incident from happening in the future are our top priority as a company", reads official blog.