Find incidents
Cyberattacks and data leaks that hit organizations in Japan. Filter by disclosure date, method, impact and status, or by where the affected organizations are, their industry or type and size.
327 results
Disclosed 2026-07-24Updated 2026-08-10 08:05Tokyo[Contained][Severity: Critical]
CMIC HealthCare Institute: RA Connect patient support program intrusion leaks 1,940 people’s data[Intrusion][Data leak]Leaked 1.9KOrganizations 1Disclosed 2026-07-22Updated 2026-09-29 08:05Tokyo[Contained][Severity: Major]
Fuso Dentsu: shared cloud folder intrusion[Credential abuse][Data leak]Leaked 26.5KOrganizations 1Disclosed 2026-07-16Updated 2026-08-05Tokyo[Resolved][Severity: Moderate]
Nissan Chemical: cloud environment unauthorized logins[Credential abuse]Organizations 1Disclosed 2026-07-14Updated 2026-09-25 08:05Tokyo[Contained][Severity: Critical]
FIVE FOXes: 59,504 member records and employee data, including bank details, may have leaked[Ransomware][Data leak][Service outage]Leaked 59.5KOrganizations 1Disclosed 2026-07-14Updated 2026-07-17Tokyo[Contained][Severity: Major]
Media4u: unauthorized access to its SMS delivery system[Web app exploit][Data leak]Leaked 95.4KOrganizations 1Disclosed 2026-07-13Updated 2026-10-30 21:22Tokyo[Investigating][Severity: Critical]
Nihon Kotsu: malware attack[Malware][Data leak][Service outage]Leaked 292.9KOrganizations 2Disclosed 2026-07-13Updated 2026-09-18Tokyo[Contained][Severity: Critical]
Nichirei: cyberattack[Intrusion][Data leak][Service outage]Leaked 43.7KOrganizations 1Disclosed 2026-07-03Updated 2026-08-17 08:05Tokyo[Contained][Severity: Major]
TV Asahi Mediaplex: server intrusion[Intrusion][Credential abuse][Data leak]Leaked 4.5KOrganizations 1Disclosed 2026-07-01Updated 2026-08-19Tokyo[Contained][Severity: Critical]
Kaga Solution Network: Academico Navi intrusion[Web app exploit][Data leak][Service outage]Leaked 170KOrganizations 3Disclosed 2026-06-30Updated 2026-09-07Tokyo[Investigating][Severity: Major]
Musashino University: shared folder ransomware[Ransomware][Service outage][Data leak]Organizations 1Disclosed 2026-06-30Updated 2026-07-31Tokyo[Contained][Severity: Critical]
Aflac Life Insurance Japan: online systems intrusion[Web app exploit][Data leak][Service outage]Leaked 4.4MOrganizations 1Disclosed 2026-06-30Updated 2026-07-14 08:05Hokkaido, Tokyo[Resolved][Severity: Major]
Norinchukin Bank: JA Sapporo production data wrongly shared in test[Misdelivery][Data leak]Leaked 3.2KOrganizations 2Disclosed 2026-06-23Updated 2026-07-06Aichi, Kagawa, Tokyo[Contained][Severity: Critical]
KDDI: unauthorized access to its mail system for ISPs[Intrusion][Data leak]Leaked 12.2MOrganizations 7Disclosed 2026-06-23Updated 2026-06-25 08:05Tokyo[Ongoing][Severity: Major]
NTTPC Communications: WebARENA transfer-server intrusion[Intrusion][Service outage]Organizations 1Disclosed 2026-06-22Updated 2026-08-25Tokyo[Investigating][Severity: Critical]
Hands Holdings: ransomware attack[Ransomware][Data leak][Service outage]Organizations 1Disclosed 2026-06-19Updated 2026-09-28Osaka, Tokyo[Contained][Severity: Critical]
Delightful: Meruhaikun mail system intrusion[Web app exploit][Intrusion][Data leak][Service outage]Leaked 1.7MOrganizations 4Disclosed 2026-06-16Updated 2026-06-16Tokyo[Resolved][Severity: Critical]
Komatsu: external user directory misconfiguration[Misconfiguration][Data leak]Leaked 139.3KOrganizations 1Disclosed 2026-06-15Updated 2026-06-15Tokyo[Investigating][Severity: Moderate]
Factory Japan Group: unauthorized access to its servers[Intrusion]Organizations 1Disclosed 2026-06-12Updated 2026-06-12Tokyo[Contained][Severity: Major]
D&M: ransomware attack[Ransomware][Data leak]Leaked 633Organizations 1Disclosed 2026-06-11Updated 2026-06-23 08:05Tokyo[Contained][Severity: Critical]
Jelly Beans Group: transfer instruction fraud[Phishing][Fraud][Financial loss]Organizations 1Disclosed 2026-06-10Updated 2026-06-10Tokyo[Contained][Severity: Critical]
Kaizen Tech Agent: suspected former employee data theft[Insider][Data leak]Leaked 9.7KOrganizations 1Disclosed 2026-06-05Updated 2026-07-31Tokyo[Contained][Severity: Critical]
Sen: unauthorized access to Hai Cheese! Photo[Web app exploit][Data leak][Service outage]Organizations 1Disclosed 2026-06-05Updated 2026-06-05Tokyo[Contained][Severity: Major]
en: Middle no Tenshoku credential stuffing[Credential abuse][Data leak]Leaked 2.5KOrganizations 1Disclosed 2026-05-30Updated 2026-07-02 08:05Tokyo[Contained][Severity: Major]
Career Design Center: Onna no Tenshoku type credential stuffing[Credential abuse][Data leak]Leaked 18.3KOrganizations 1Disclosed 2026-05-28Updated 2026-05-28Tokyo[Contained][Severity: Major]
Asoview: satsuki intrusion[Intrusion][Data leak]Leaked 27.2KOrganizations 1Disclosed 2026-05-28Updated 2026-05-28Tokyo[Investigating][Severity: Critical]
Polaris Holdings: Booking.com account intrusion[Credential abuse][Fraud][Financial loss]Organizations 1Disclosed 2026-05-21Updated 2026-08-14Tokyo[Contained][Severity: Critical]
Geniee: unauthorized access to GENIEE MA[Credential abuse][Financial loss]Organizations 1Disclosed 2026-05-15Updated 2026-05-15Tokyo[Resolved][Severity: Moderate]
CS Accounting: unauthorized access to its servers[Credential abuse]Organizations 1Disclosed 2026-05-14Updated 2026-09-11Tokyo[Contained][Severity: Major]
Nihon Shisan Souken: ransomware attack[Ransomware][Credential abuse][Data leak][Service outage][Extortion]Organizations 1Disclosed 2026-05-12Updated 2026-07-31Tokyo[Contained][Severity: Critical]
Tokyo Hoso Kogyo: ransomware attack[Ransomware][Data leak]Organizations 1Disclosed 2026-05-12Updated 2026-05-12Tokyo[Investigating][Severity: Major]
Oriental Diamond: ransomware attack[Ransomware][Data leak][Service outage]Organizations 1Disclosed 2026-05-09Updated 2026-05-27Tokyo[Contained][Severity: Critical]
Matsuzawa Shoten: ransomware attack[Ransomware][Service outage]Organizations 1Disclosed 2026-05-08Updated 2026-05-13 08:05Tokyo[Contained][Severity: Critical]
Nihon Wasou Holdings: transfer instruction fraud[Phishing][Fraud][Financial loss]Organizations 1Disclosed 2026-05-07Updated 2026-06-30Tokyo[Contained][Severity: Major]
East: unauthorized access to its internal network[Intrusion][Data leak]Organizations 1Disclosed 2026-05-01Updated 2026-06-23Tokyo[Contained][Severity: Major]
Money Forward: unauthorized access to its GitHub[Credential abuse][Data leak]Leaked 60.4KOrganizations 1Disclosed 2026-04-28Updated 2026-05-01 08:05Tokyo[Investigating][Severity: Moderate]
Cabinet Office Okinawa General Bureau: FileZen server breach[Intrusion][Data leak]Organizations 1Disclosed 2026-04-24Updated 2026-07-28 08:05Tokyo[Contained][Severity: Critical]
Hatena: transfer instruction fraud[Phishing][Fraud][Financial loss]Organizations 1Disclosed 2026-04-24Updated 2026-05-14 08:05Aichi, Tokyo[Investigating][Severity: Moderate]
Aioi Nissay Dowa Insurance: secondee improperly shares Toyota data[Insider][Data leak]Organizations 2Disclosed 2026-04-24Updated 2026-04-27 08:05Aichi, Tokyo[Investigating][Severity: Moderate]
Mitsui Sumitomo Insurance: secondees leak Toyota data[Insider][Data leak]Organizations 2Disclosed 2026-04-23Updated 2026-06-19Tokyo[Contained][Severity: Critical]
Yellow Hat: 2Rinkan app API data theft[API abuse][Data leak][Service outage]Leaked 3.5MOrganizations 1Disclosed 2026-04-19Updated 2026-06-15 08:05Tokyo[Resolved][Severity: Major]
BELFOR Japan: INC Ransom data theft[Ransomware][Data leak][Service outage]Organizations 1Disclosed 2026-04-14Updated 2026-05-07 08:05Tokyo[Contained][Severity: Major]
Start dash: Kyuun account data offered for sale[Intrusion][Data leak]Leaked 39.3KOrganizations 1Disclosed 2026-04-10Updated 2026-06-12Tokyo[Contained][Severity: Moderate]
UPSIDER: open source software supply chain attack[Malware][Service outage]Organizations 1Disclosed 2026-04-10Updated 2026-05-01 08:05Tokyo[Resolved][Severity: Moderate]
T&D Holdings: agency secondees improperly take information[Insider][Data leak]Organizations 1Disclosed 2026-04-09Updated 2026-04-09Tokyo[Contained][Severity: Major]
NYK: marine fuel procurement system intrusion[Intrusion][Data leak][Service outage]Organizations 1Disclosed 2026-04-08Updated 2026-04-30Tokyo[Investigating][Severity: Major]
ielove GROUP: ielove CLOUD intrusion[Credential abuse][Web app exploit][Data leak]Organizations 1Disclosed 2026-04-03Updated 2026-06-02Kanagawa, Tokyo[Contained][Severity: Critical]
CAMPFIRE: unauthorized access to its GitHub account[Credential abuse][Data leak]Leaked 225.8KOrganizations 2Disclosed 2026-03-27Updated 2026-04-14 08:05Tokyo[Contained][Severity: Critical]
ZUU: transfer instruction fraud[Phishing][Fraud][Financial loss]Organizations 1Disclosed 2026-03-27Updated 2026-04-08 08:05Fukuoka, Tokyo[Investigating][Severity: Moderate]
Bank of Fukuoka: MetLife secondee leaks policy data[Insider][Data leak]Organizations 2Disclosed 2026-03-24Updated 2026-04-27Tokyo[Contained][Severity: Major]
Cynd: BeautyMerit intrusion[Unknown][Data leak]Organizations 1