SHINDO3

KBC Gakuen Educational Foundation

Parents and guardians2,471people

LEAK CONFIRMEDPostal address / Full nameMisdelivery · Closed (final report)

Open in the live monitor ▶
Disclosed
Aug 17, 2026
Detected
Aug 3, 2026
Detection to disclosure
14 days
Leak
Leak confirmed
Type
Misdelivery
Status
Closed (final report)
Security spend
Not checked yet
Compensation
Not announced

What leaked

IdentityFull name
ContactNames and addresses

How many

  • Parents and guardians 2,471 people

Who is affected

  • Parents and guardians

Cause

A row was deleted by mistake when preparing the mailing data, so names and addresses were shifted by one line

Timeline

  1. Found after a parent got in touch
  2. Corrective notices sent
  3. First disclosure

Response

  • Notified individuals
  • Change process

Sent corrective notices by August 12; data preparation and mailing will be checked and cross-checked by several people

What you should do

  1. Watch for unexpected mail or invoices; your address is hard to change
  2. You can be affected without ever using this service (parcel recipients etc.). Check any notice you receive
  3. Check the company's notice to see if you're affected

Lessons for companies

  1. Use DLP: recipient checks, send delay, automatic attachment protection
  2. Report to the PPC: preliminary in 3–5 days, final in 30 (60 if malicious)
  3. Run red teaming and AI-assisted hardening, and publish how much you invest

Sources