Overview
J:COM NET email addresses of 2,473,191 people, partner cable-operator mail users 118,752 (corrected July 21), passwords of 1,257. Count left blank because the categories differ and are not summed. This stems from the intrusion into KDDI's mail platform for ISPs (recorded separately); the figure is a subset of KDDI's total and must not be added to it.
Timeline
- Occurred
- Discovered
- Disclosed
Organization response
Per the notice, the organisation investigated and contained the incident, notified individuals and offered monitoring or protective resources.
What you can do
Be wary of emails, SMS or calls impersonating the organisation; do not open links or attachments or enter passwords or card details. Change reused passwords on other services.
Sources
- （更新）当社メールサービスに対する不正アクセスの発生についてJCOM株式会社 · 2026-11-09