ドン・キホーテ、長崎屋、橘百貨店、UDリテール（委託先: コックス）Data breach / unauthorized access incident
- Occurred on
- September 15, 2026
- Announced on
- October 28, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- Unknown
- Main impact
- A server containing names of customers who requested watch repairs, portions of their addresses, and parts of their phone numbers was encrypted by ransomware, has not been restored, and an external data leak cannot be ruled out.
- Information involved
- Full nameHome addressPhone number
- Cause / key point
- An external cyberattack reportedly encrypting the server with ransomware.About Ransomware
- Industry
- Retail & e-commerce
- Last updated
- October 29, 2026
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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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Same attack method
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Same industry
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Attack method classification: Ransomware(Encrypting data and demanding a ransom)
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