Marissa Mayer

Yahoo suffers world's biggest hack affecting 1 billion users

Yahoo suffers world's biggest hack affecting 1 billion users

Yahoo has discovered a 3-year-old security breach that enabled a hacker to compromise more than 1 billion user accounts, breaking the company's own humiliating record for the biggest security breach in history.

The digital heist disclosed Wednesday occurred in August 2013, more than a year before a separate hack that Yahoo announced nearly three months ago. That breach affected at least 500 million users, which had been the most far-reaching hack until the latest revelation.

"It's shocking," security expert Avivah Litan of Gartner Inc.

Both lapses occurred during the reign of Yahoo CEO...

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