2026 Seicomart — ~570k club-app accounts; names, addresses, phones, emails
Data compromised
About 570,000 user IDs may have had name, gender, DOB, address, phone, email, and club-card join/leave dates viewed. Passwords not leaked; company does not hold credit-card data. No confirmed Peko Mama Money e-money misuse at notice time.
Technical writeup
Verified company notice — Seicomart (Hokkaido-centered convenience chain) announced Sep 29, 2026 that unauthorized access to the Seicomart Club app member server may have exposed personal data for ~570,000 accounts: name, gender, DOB, address, phone, email, club join/leave dates. Triggered by a suspicious cancellation Sep 24 evening; unauthorized server access found Sep 28 after 17:00; server disconnected by 20:00. Passwords not compromised; no card storage; e-money misuse not observed. App functions for registration/profile/cancellation/My Page suspended pending investigation. recordsAffected 570000; companyConfirmed true.
Root cause
Unauthorized access to Seicomart Club member-information server via the smartphone app path; suspicious club-card cancellation Sep 24 led to discovery; server access confirmed ~Sep 28 17:00; disconnected ~20:00 (company notice).