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[Investigating][Severity: Moderate][Unknown]

Mizuho Leasing: unauthorized access to a power investment system

Mizuho Leasing confirmed on 14 December 2025 that part of its systems had been accessed without authorization and disclosed it on 6 January. The system handles power generation investments and runs on separate external infrastructure from the core systems; it was cut off. At disclosure no business impact or data leak had been confirmed.

Disclosed

2026-01-06

Organizations involved

1

Leaked or at risk

Unknown

Downtime

Unknown

Timeline

  1. Detected 2025-12-14
  2. Disclosed 2026-01-06
  3. 23 days

Attack or cause

Method
[Unknown]
Impact
Entry point
Unknown

Data exposed or at risk

–

Organizations involved

Open in organization search

Sources

  1. [1][Official]当社システムに対する不正アクセスについてMizuho Leasing · 2026-01-06