Overview
34,330 unique people including former insured. FY2013 go-live eligibility and claims data retained contrary to the contract.
Timeline
- Occurred
- Discovered
- Disclosed
Organization response
Per the notice, the organisation investigated and contained the incident, notified individuals and offered monitoring or protective resources.
What you can do
Be wary of emails, SMS or calls impersonating the organisation; do not open links or attachments or enter passwords or card details. Change reused passwords on other services.
Sources
- 業務を委託する事業者におけるサイバー攻撃による不正アクセスについて（第2報）令和8年5月25日幸手市 · 2026-11-09
- サイバー攻撃による不正アクセスについて（第1報）令和8年4月17日幸手市 · 2026-11-09