Confirmed

Seicomart: app-mediated intrusion into member servers led to viewing of 574,647 club members’ data

Unauthorized access reached member servers via the Seicomart app. First notice Sep 29, 2026 cited ~570k accounts; fourth notice Oct 5 fixed 574,647 people (name, sex, DOB, address, phone, email). Passwords/cards out of scope. First disclosure remains Sep 29.

Last updated: 2026-11-09

Overview

574,647 people (fourth-notice figure).

Timeline

UnknownOccurred
2026-09-28Discovered
2026-09-29Disclosed

Organization response

Per the notice, the organisation investigated and contained the incident, notified individuals and offered monitoring or protective resources.

What you can do

Be wary of emails, SMS or calls impersonating the organisation; do not open links or attachments or enter passwords or card details. Change reused passwords on other services.

Sources

「セイコーマートアプリ」への不正アクセスによる個人情報の閲覧に関するお詫びとお知らせ（第四報）株式会社セイコーマート · 2026-11-09
「セイコーマートアプリ」への不正アクセスによる個人情報流出の可能性に関するお詫びとお知らせ株式会社セイコーマート · 2026-11-09

Seicomart: app-mediated intrusion into member servers led to viewing of 574,647 club members’ data

Overview

Timeline

Organization response

What you can do

Sources

Related information

No published information yet

Comments and replies

Write a comment