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kb-kookmin-2026 · Disclosed 2026-10-02

KB Kookmin Bank: employee work-support system data leak

The bank disclosed data leakage involving 99 customers and 20 current or former employees from its mobile work-support system, separate from internet banking.

Cause unresolved / undisclosed

Outcome: Confirmed breach

Entry path and evidence

  • Reported fact

    99 customers were affected across up to 17 fields and 20 current/former employees across up to seven; fields differ by individual.

    [s1]本文 流出対象と項目
  • Reported fact

    The bank describes the employee work-support system as unrelated to internet banking and financial transactions.

    [s1]本文 冒頭

Timeline

  1. Confirmed leakage; this is not an established intrusion start. [s1]

  2. Published notification to affected customers and employees. [s1]

Reported response

  • Reported fact

    Stopped affected systems and servers, blocked access routes and strengthened abnormal-access monitoring.

    [s1]本文 対応

Cause and mitigation hypotheses

Not assessed. Editorial hypotheses have not been added for this incident; this does not establish safety or a confirmed cause.

Evidence relevant to prevention

Insufficient evidence

The exact entry method and prior controls are unresolved. Inspect exposure, privileges and logs using the linked rules.

Editorial assessment; not a determination of liability. [s1]

Unknowns and AI involvement

AI involvementUnknown

The reviewed primary evidence does not establish attacker AI use in this incident.

Entry, links to other incidents and AI use are unresolved. The FSC total of 16 firms and about 100,000 records is separate and is not added to this bank’s people count.

Sources

  1. [s1] KB国民銀行 · Primary source

    개인(신용)정보 유출 관련 안내 ↗

    Published 2026-10-02 · Reviewed 2026-10-26

  2. [s2] 韓国金融委員会 · Primary source

    금융권 침해사고 재발방지를 위해 금융보안 관리체계를 전면 강화하겠습니다. ↗

    Published 2026-10-14 · Reviewed 2026-10-26