セイコーマートアプリData breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- September 30, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 574,647 people
- Main impact
- Information of 574,647 members was improperly accessed, including names, addresses, dates of birth, emails, etc., but passwords are reported not to have been leaked.
- Information involved
- Email addressPhone numberHome addressFull nameDate of birth
- Cause / key point
- Cause is under investigation.
- Industry
- IT & telecom
- Listing / capital
- Unlisted
セイコーマート is not publicly listed.
- 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
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Attack method classification: Under investigation / not stated(Cause not disclosed)
Read the Under investigation / not stated guide and national trends →