It may be one of the largest cybersecurity breaches ever… Yahoo says data associated with at least 500-million user accounts has been stolen. The company says it believes a state-sponsored actor was behind the data breach — Meaning a person acting on behalf of a government. The breach is believed to have taken place in late 2014. Yahoo says account information stolen may include names, email addresses, phone numbers, dates of birth, passwords and security questions and answers. Yahoo users are urged to change their password and security questions and review their accounts for suspicious activity.