ヤマト運輸(クロネコ代金後払いサービス)Data breach / unauthorized access incident
- Occurred on
- September 28, 2026
- Announced on
- September 29, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 5,310,000 records
- Main impact
- User information from クロネコ代金後払いサービス was leaked. The affected subset covers some usage since 2018年10月以降, with about 531万件 impacted including names, addresses, phone numbers and order details, of which about 49万件 reportedly included email addresses; about 5万件 of recipient information and about 4,100件 of merchant information were also included. The company stated that credit card information and passwords were not included, and no fraudulent use has been confirmed to date; the unauthorized access was discovered in 9月末 and the service was temporarily suspended and later partially resumed on some dates.
- Information involved
- Email addressPhone numberHome addressFull name
- Cause / key point
- The company reported that user information was taken through unauthorized access by a third party (unauthorized access confirmed on 2026年9月28日).
- Last updated
- October 21, 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
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Attack method classification: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →