Skip to content
JAENES
BLeak confirmedOctober 6, 2026 announced

長崎市（イベント招待文の誤送付）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
September 18, 2026
Announced on
October 6, 2026
Severity
BIncidents centered on names and contact details.
Scale
1 people
Main impact
An informational letter for a welfare commissioner was mistakenly placed on top of an envelope addressed to another welfare commissioner and enclosed, resulting in one person's name and address being disclosed externally.
Information involved
Home addressFull name
Cause / key point
The cause is under investigation.
Industry
Government & municipal
Listing / capital
Government / public body

Municipality: 長崎市

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

Related incidents

Browse the database →

Incidents sharing the same company, service, attack method or industry (grouped automatically from the disclosures).

Other incidents at 長崎市

Incidents related to "イベント"

Incidents where the damage spread through the same service or system.

Same industry

Attack method classification: Under investigation / not stated(Cause not disclosed)

Read the Under investigation / not stated guide and national trends →

← Back to Breach Watch