イエローハット（WEB作業予約）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- August 28, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 1,797,124 people
- Main impact
- Personal data of 1,797,124 イエローハット members, including names, addresses, dates of birth, member numbers and login IDs, and passwords in an unrecoverable state were leaked.
- Information involved
- Email addressUser / member IDPasswordPhone numberHome addressFull nameDate of birth
- Cause / key point
- An attack by a malicious program against the WEB作業予約システム.
- Industry
- Retail & e-commerce
- Listing / capital
- Listed company東証プライム 9882(イエローハット)
- Sources
- Last updated
- October 20, 2026
Stock price reaction to the disclosureイエローハット / 東証プライム 9882
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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 industry
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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 →