ゼットン（forty three旧メール）Data breach / unauthorized access incident
- Occurred on
- November 27, 2025
- Announced on
- March 27, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 18,553 records
- Main impact
- They disclosed that unauthorized access to two old email accounts may have resulted in the exposure of 18,553 customers' information.
- Information involved
- Email addressAuth tokenPhone numberHome addressFull nameHealth & medical data
- Cause / key point
- They say malware infection led to credential theft, and those credentials were used for unauthorized logins and to send emails.About Abuse of credentials
- Industry
- Retail & e-commerce
- Listing / capital
- Unlisted
- 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
Related incidents
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Incidents where the damage spread through the same service or system.
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Same attack method
- A日本経済新聞社(日経)2026.10.16 announced・Affected 1,830,000 records
- Sチャーム本店2026.09.01 announced・Affected 370,000 records
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Same industry
- S阪急阪神百貨店（H2O ID等）2026.10.19 announced・Affected 1,260,000 records
- Sパピレス（Renta!）2026.10.19 announced・Affected Unknown
- Sジグザグ（WorldShopping）2026.10.19 announced・Affected 301 people
- Sブックオフグループ(ブックオフコーポレーション)2026.10.09 announced・Affected 6,383,279 people
- Sアクティブ（通販サイト）2026.10.06 announced・Affected 54,916 records
- SMrMax2026.10.06 announced・Affected 1,735,154 people
Attack method classification: Abuse of credentials(Logging in legitimately with leaked or guessed passwords)
Read the Abuse of credentials guide and national trends →