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JAENES
BLeak confirmedOctober 8, 2026 announced

大阪歴史博物館（ボランティア連絡）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
October 7, 2026
Announced on
October 8, 2026
Severity
BIncidents centered on names and contact details.
Scale
4 people
Main impact
Email addresses of four volunteers (for one of whom the name was also included) were sent in CC instead of BCC and exposed; deletion has been requested from the recipients.
Information involved
Email addressFull name
Cause / key point
Incorrect entry into the CC field and failure to perform a multi-person check of recipients.
Industry
Government & municipal
Listing / capital
Government / public body
Sources
Last updated
October 20, 2026
Email 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: Under investigation / not stated(Cause not disclosed)

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

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