Yahoo is sending messages to some users alerting them to the use of forged cookies to access their data in a third breach of customer accounts in 2015-2016, CNBC reports. Some of these hacks are attributed to a "state-sponsored actor" also involved with the 2014 Yahoo breach in which 500 million accounts were compromised.
Yahoo did not reveal the number of accounts affected by the third breach but confidential data, including email addresses and security details, were compromised in the incident disclosed last December.
A company spokesperson said: "The investigation has identified user accounts for which we believe forged cookies were taken or used. Yahoo is in the process of notifying all potentially affected account holders."
The three incidents have been bad news for Yahoo, particularly because the company has been in a takeover deal with Verizon Communications. Bloomberg reports the breach disclosures have allowed Verizon to renegotiate the deal and reduce the decided purchase price of $4.8 billion by $250 million.
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