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Yahoo Confirms Breach of Over 1 Billion Accounts Linked to State-Sponsored Actors

Yahoo Confirms Breach of Over 1 Billion Accounts Linked to State-Sponsored Actors

First seen 3 Jun 2026, 20:43 UTC • •

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ThreatCluster AI
ThreatCluster •June 4, 2026 at 20:39 UTC
  • •Yahoo's breach affects over 1 billion accounts, making it the largest in history.
  • •The attack involved state-sponsored actors using forged cookies for unauthorized access.
  • •Yahoo is mandating password changes for all affected users and has invalidated compromised cookies.

Yahoo has disclosed a massive data breach affecting more than one billion user accounts, which occurred in August 2013. This breach is separate from a previously reported incident in 2014 that compromised 500 million accounts. The company believes state-sponsored actors are involved, utilizing sophisticated methods to forge cookies that allowed unauthorized access without passwords. Affected data may include names, email addresses, phone numbers, dates of birth, and hashed passwords. Yahoo is notifying all impacted users and mandating password changes. The breach raises concerns about the company's security practices and could impact Verizon's acquisition deal. Forensic experts are still investigating the specifics of the intrusion, which remains unidentified.

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Updated 143d ago How this analysis works

Timeline

2013-08-01
Data breach occurred
Unauthorized access to over one billion user accounts took place, linked to state-sponsored actors.
Digitaljournal
2016-09-01
Previous breach disclosed
Yahoo reported a separate breach affecting 500 million accounts, leading to increased scrutiny.
TechCrunch
2026-06-03
Yahoo announces new breach
Yahoo confirmed the breach of over one billion accounts, stating it is distinct from the 2014 breach.
The Guardian
2026-06-03
User notifications begin
Yahoo starts notifying affected users and mandates password changes to enhance security.
Digitaljournal

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