> JapanHacked_
[Contained][Severity: Critical][Web app exploit]

Mr Max: unauthorized access to its app and online store

On the evening of 3 October, discount store chain Mr Max found suspicious access to the servers of its MrMax app and online store, stopped the services and blocked outside access. A third party had abused a function of the software the services run on to get into the server, and member IDs, names, emails and phone numbers of up to 1,735,154 people leaked. Addresses, birth dates, card data, passwords and purchase history did not leak.

Disclosed

2026-10-06

Organizations involved

1

Leaked or at risk

1.7M

1,735,154

Downtime

Unknown

Timeline

  1. Detected 2026-10-03
  2. Disclosed 2026-10-06
  3. 3 days

Attack or cause

Method
[Web app exploit]
Impact
[Data leak][Service outage]
Entry point
Web app

Data exposed or at risk

[Name][E-mail address][Phone number]

Organizations involved

Open in organization search

Sources

  1. [1][Official]不正アクセスによる情報流出に関するお詫びとお知らせMr Max · 2026-10-06
  2. [2][News]ミスターマックス、不正アクセスで最大173万人の会員情報流出Reuters · 2026-10-06