Z-kai: unauthorized logins to the Z-ID system
In the early hours of 15 October, 13 passwords were changed in quick succession through the password reset function of Z-ID, the login system for Z-kai group services; Z-kai found it at about 11:00 that day. Names, emails and Z-IDs of the 13 accounts may have been viewed. The accounts were suspended, and the password reset function was paused and reopened with stronger security.
Disclosed
2026-10-19
Organizations involved
1
Leaked or at risk
13
13
Downtime
Unknown
Timeline
- Started, Detected 2026-10-15
- Disclosed 2026-10-19
- 4 days
Attack or cause
- Method
- [Web app exploit]
- Impact
- [Data leak]
- Entry point
- Web app
Data exposed or at risk
Services hit
Organizations involved
[Breached][Major]Shizuoka, MishimaEducation and learning support13 leaked
Z-kai Inc.
Sources
- [1][Official]Z-IDシステムへの不正ログインについて（第一報）Z-kai · 2026-10-19