Yahoo Inc. suffered a data breach in 2014 that affected at least 500 million Yahoo user accounts, the company announced Thursday.
The Sunnyvale, Calif., Internet firm said the hacker is believed to be a “state-sponsored actor” and may have gained access to user information such as names, email addresses, telephone numbers, dates of birth, scrambled passwords, and some encrypted and unencrypted security questions and answers.
Yahoo said hackers did not steal unprotected passwords or credit card and bank account information.
The company did not say how long it had known about the data breach. It did not immediately respond to a request for...