Maru-Jan leak exposes emails and passwords of all 1,855,578 members
The passwords and registered email addresses of all 1,855,578 members of Maru-Jan, an online mahjong service operated by Japan’s SignalTalk, were downloaded externally. The attacker exploited a function in the administration system. After emergency maintenance and blocking the intrusion route, the operator resumed the service on November 7, 2026, and asked members to change their passwords.
Key facts
- Affected organization
- SignalTalk
- Incident type
- Data breach
- Occurred / detected
- Not confirmed
- Scale of damage
- Passwords and registered email addresses of all 1,855,578 members leaked
- Cause / method
- Unauthorized access and downloading of member information by exploiting a function in the administration system
- Location
- Japan
If your data was exposed
Exposed dataEmailPassword
- Change your password, and also change it on any other site where you use the same one. Turn on two-factor authentication if available.
- Don’t tap links in texts, calls or emails that mention this incident and offer compensation, refunds or breach checks. Check directly on the organization’s official website or app.
Timeline
- The operator announced the leak of information belonging to all 1,855,578 members and resumed the service after addressing the intrusion route.
- It was disclosed that the intrusion route had been blocked and members had been asked to change their passwords.
12 related reports
- Maru-Jan(シグナルトーク)の情報漏えい(2026年・約186万人)原因・補償・その後|セキュリティ事故カルテ
- オンライン麻雀「Maru-Jan」に不正アクセス、全会員 1,855,578人分のメールアドレスとパスワードが流出
- ステップゴルフの情報漏えい(2026年・約22万件)対象者・補償・原因
- オンライン麻雀「Maru-Jan」への不正アクセスによる会員情報流出のお詫びとご報告
- オンライン麻雀「Maru-Jan」への不正アクセスによる個人情報の流出をシグナルトークが発表
- オンライン麻雀「Maru-Jan(マルジャン)」、不正アクセスで会員185万5,578人のパスワードが流出 管理システムの機能悪用、11月7日にサービス再開
- シグナルトークのMaru-Janで会員185万5,578人分のパスワードが流出
- Maru-Jan says email addresses and passwords of 1,855,578 members were taken
- Maru-Jan Data Breach: Email and Password Leak
- Maru-Jan 不正アクセス 情報流出 パスワード変更 シグナルトーク
- オンライン麻雀「Maru-Jan」に不正アクセス、会員185万人分のパスワードが流出
- オンライン麻雀に不正アクセス 会員情報流出 ~ 寄せられた激励メッセージに謝意 メールはスタッフ全員が目を通し必ず返信
The summary and key facts are written by AI from related reports and may contain errors. Check the original articles and the organization’s official statements for accurate details.