Yahoo says a massive data breach earlier this year may have affected as many as 500 million accounts.
According to Yahoo, compromised user account info may have included names, email addresses, dates of birth, and in some cases, security questions and answers.
In a statement, Yahoo said a “state-sponsored actor” is believed to be behind the hack, but added the company “found no evidence that the state-sponsored actor is currently in Yahoo’s network.”
The data was stolen from Yahoo in late 2014, according to the company.
Potentially affected users were being notified by Yahoo to take steps to secure their accounts, including password changes and invalidating unencrypted security questions and answers so that they cannot be used to access an account.
Users who haven’t changed their passwords since 2014 were being urged to do so.
A report from the cyber tech website Recode said the data breach came to light last month when a hacker known as “Peace” claimed to be selling credentials for millions of Yahoo users from 2012.