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BLeak confirmedOctober 6, 2026 announced

長崎市（特別徴収税額決定通知の誤送付）Data breach / unauthorized access incident

笹尾 祐太朗の写真Reviewed by Yutaro SasaoWritten by Leak Watch editorial team published ・ updated
Occurred on
May 18, 2026
Announced on
October 6, 2026
Severity
BIncidents centered on names and contact details.
Scale
1 people
Main impact
A notice of determined special withholding tax amount (including address, name, etc.) was mistakenly sent to a different business with the same name, resulting in one person's personal information being disclosed externally.
Information involved
Home addressFull name
Cause / key point
Cause under investigation.
Industry
Government & municipal
Listing / capital
Government / public body

Incident involving a local government.

Sources
Last updated
October 20, 2026
Home addressFull nameHow severity is assessed →

Is this incident worth paying attention to?

Written & reviewed

笹尾 祐太朗の写真

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: Misdirected sending & disclosure (human error)(Leaks caused by wrong recipients or exposure settings)

Read the Misdirected sending & disclosure (human error) guide and national trends →

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