Another data breach?
Yahoo have said more than one billion user accounts may have been affected by a hacking attack which dates back to May 2013.
The company said this incident appeared to be different from a 2014 breach disclosed in September when 500m accounts had been accessed.
Yahoo said names, passwords, email addresses and phone numbers were stolen. However, no bank and payment data was taken.
The company is currently working closely with the police and authorities.
Yahoo “believes an unauthorised third party, in August 2013, stole data associated with more than one billion user accounts”.
The three-year hack was uncovered due to ongoing investigations into the 2014 breach.
Account users have been urged to change passwords and security questions.
Yahoo has more than a billion monthly active users, some however may have more than one account. There are also many accounts which aren’t used very often or lay dormant.
Cyber security expert Troy Hunt told the BBC: “This would be far and away the largest data breach we’ve ever seen. In fact, the 500m they reported a few months ago would have been, and to see that number now double is unprecedented.”
Yahoo, who is being taken over by Verizon said the attack could be linked to state-sponsored activity, as with the previous attack.