> JapanHacked_
[Contained][Severity: Major][Unknown]

Mynavi: unauthorized access to a cloud service it uses

An anomaly in a cloud service was detected and external access blocked on December 5, 2025. Possible exposure was established January 16 and disclosed February 12, 2026. The March 31 report listed 74,224 service-user, 21,609 business-contact and 15,672 group-employee records. The incident did not involve its service websites or their databases; no service impact or secondary harm was found.

Disclosed

2026-02-12

Organizations involved

1

Leaked or at risk

74.2K

74,224

Downtime

Unknown

Timeline

  1. Detected 2025-12-05
  2. Disclosed 2026-02-12
  3. 69 days

Attack or cause

Method
[Unknown]
Impact
[Data leak]
Entry point
Unknown

Data exposed or at risk

[Name][E-mail address][Postal address][Phone number][Employment]

Organizations involved

Open in organization search

Sources

  1. [1][Official]当社が利用するクラウドサービスに対する不正アクセスの発生および個人情報流出の可能性についてMynavi · 2026-02-12
  2. [2][Official]利用するクラウドサービスに対する不正アクセスの発生および個人情報流出の可能性について（第三報）Mynavi Corporation · 2026-03-31