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[Investigating][Severity: Major][Intrusion]

MHLW: JANIS cyberattack puts up to 11,652 medical-institution contacts’ data at risk

A data-stealing program on JIHS-operated JANIS servers puts up to 11,652 medical-institution contacts’ data at risk. The system is stopped.

Disclosed

2026-11-06

Organizations involved

2

Leaked or at risk

11.7K

11,652

Downtime

Unknown

People affected or at risk

11.7K

11,652

Contracted system investigation and suspension

JIHS, MHLW’s contracted operator, reported a data-stealing program placed on the JANIS web server that may have run. At-risk information includes up to 11,652 medical-institution contacts’ names, titles, phones and email, plus hospital names, bed counts, institutional addresses/postcodes and registered resistant-organism data. Contact and institutional/surveillance data are distinguished; patient medical-history exposure is not established. [1]

The system is stopped to prevent further harm while cause and impact are investigated. Individual notification is planned and secondary misuse is not confirmed. An earlier 27 October item on the page announced a safety-related suspension; suspected exposure was disclosed on 6 November. [1]

Timeline

  1. Disclosed 2026-11-06
  2. 1 days

Attack or cause

Method
[Intrusion]
Impact
[Data leak][Service outage]
Entry point
Unknown

Data exposed or at risk

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

Supply chain

Services hit

Organizations involved

Open in organization search

Sources

  1. [1][Official]薬剤耐性菌発生動向調査システムに係る個人情報等の漏えい疑いについてMHLW · 2026-11-06