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Arcadia disaster information system data breach

Updated 1 time since CLSTR started tracking revisions of this situation.

What changed

2026-10-16 03:23 UTC → 2026-10-21 09:53 UTC · added removed

A major cybersecurity breach involving the IT company Arcadia has compromised the SpeeCAN RAIDEN disaster information distribution system in Japan. The unauthorized access targeted a system used by approximately 800 local governments to disseminate emergency alerts and weather warnings. Arcadia reported that the breach could affect up to 3,136,000 email addresses and 105,000 phone numbers. Affected municipalities include Kyoto, Aomori, Akita, and Wakayama. Specific reports indicated potential leaks of resident emails, staff details, and even facial photographs in certain cities. Following the incident, several municipalities suspended emergency services, such as disaster email alerts and reporting systems. By mid-October, disaster prevention systems in regions including Toyama and Akita prefectures began resuming operations. Local authorities, such as In Toyama, Takaoka City restored multilingual and fax-based email services on October 15, noting that approximately 4,700 names, emails, and phone numbers may have been leaked. Similarly, Yokote City, reported receiving Kazuno City, and Kosaka Town in Akita Prefecture resumed distributions, with Yokote City reporting instances of suspicious emails during the service downtime and continue to investigate the full extent downtime. The scope of the breach has expanded to include law enforcement. Approximately 125,000 police officers and staff across 20 prefectural police departments—including Kanagawa, Hyogo, Saitama, and Aichi—have potentially had their personal information exposed. Leaked data compromise. reportedly includes names, affiliations, email addresses, and private mobile numbers used for emergencies. Additionally, the breach impacted roughly 16,000 private citizens and 2,600 corporations registered for crime prevention services in Kyoto, Shimane, Yamaguchi, and Fukuoka. The National Police Agency is investigating the incident alongside Arcadia.

Versions

  1. 2026-10-21 09:53 UTC Arcadia disaster information system data breach
  2. 2026-10-16 03:23 UTC Arcadia disaster information system data breach

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