City of Yokohama security incident history
Hacking, data breaches and other security incidents involving City of Yokohama, with related coverage.
Incidents: 1 · Most recent
508 email addresses leaked from Yokohama facility booking system
↳ Knock-on damage from the Arara incident · View original incident508Impact: 508 email addresses exposed: 443 belonging to user organizations and 65 belonging to facilities
Unauthorized access to Arara's email delivery service exposed 508 email addresses associated with Yokohama's booking system for facilities including community care plazas: 443 belonging to user organizations and 65 belonging to facilities. The city was notified of the unauthorized access and service suspension on October 28, 2026, confirmed the scale of the leak on November 9, and announced it on November 10.
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