デジタル庁Data breach / unauthorized access incident
- Occurred on
- May 25, 2026
- Announced on
- September 11, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 246,000 people
- Main impact
- Approximately 189,000 government employees and about 57,000 private-sector-related individuals — a total of approximately 246,000 people — may have had names, email addresses, phone numbers, and addresses leaked. No misuse has been confirmed at this time.
- Information involved
- Email addressPhone numberHome addressFull name
- Cause / key point
- Unauthorized access by a third party occurred using a maintenance/operations staff account on the common system for ministries and agencies, ガバメントソリューションサービス（GSS）.
- Industry
- Government & municipal
- Listing / capital
- Government / public body
- Last updated
- October 20, 2026
Is this incident worth paying attention to?
Written & reviewed
Reviewed byYutaro SasaoFounder & CEO, MediaLeap Inc.
CEO of MediaLeap Inc. Working on both sides of web advertising and web media since 2013; founded the company in May 2025.
Review scope: cross-checking against primary sources (official and government announcements), verifying claims stay within the facts, and checking source attribution。Last reviewed:
Written by:Leak Watch editorial team (AI-assisted drafts verified against sources by the editorial team) · Reviewer profile · Request a correction
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Attack method classification: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →