BookOff Confirms External Transmission of Member Data — 6,383,279 People Affected, Including Former Members
SUMMARY
Following its initial notice on October 9, ブックオフコーポレーション announced in a second report on October 13 that it confirmed external transmission from its membership management system. The affected data covers 6,383,279 people (6,427,735 membership records), including about 210,000 former members, and includes names, dates of birth, addresses, phone numbers, email addresses, and password hashes. The incident relates to unauthorized access from October 4–6.
At the time of the first report the company had described the situation as a "possibility of leakage," but it has now confirmed that data was transmitted externally. Passwords were stored in hashed form; however, because hashes can potentially be cracked via brute-force attacks, the company is instructing all users to reset their passwords.
Information combinations such as name, address, and date of birth accumulated even for casually registered services like point cards contributed to the scale of this breach. Minimizing the collection of registration information is an important issue to be raised from the user perspective as well.
- #data breach
- #password hash
- #personal data
Source
ブックオフ 公式お詫びとお知らせ — https://www.bookoff.co.jp/info/news/2026/post_113.htmlThis article summarizes the content of the source below. Refer to the original source for accuracy. Last updated: October 18, 2026
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