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 2026-09-29Updated 2026-10-14Tokyo[Investigating][Severity: Critical]
Unirita: document management system intrusion[Intrusion][Data leak][Extortion]Organizations 1Disclosed 2026-09-29Updated 2026-09-30Tokyo[Contained][Severity: Major]
Japan Post: unauthorized access to the Post Office App[Intrusion][Data leak][Service outage]Leaked 69Organizations 2Disclosed 2026-09-29Updated 2026-09-30Tokyo[Resolved][Severity: Critical]
TOPPAN: Sompo Japan policyholder data sent to another insurer[Misdelivery][Data leak]Leaked 177.4KOrganizations 2Disclosed 2026-09-29Updated 2026-09-29Tokyo[Contained][Severity: Critical]
eplus: unauthorized access to the e-ticket refund system[Intrusion][Data leak]Leaked 1.5KOrganizations 1Disclosed 2026-09-28Updated 2026-10-09Tokyo[Contained][Severity: Critical]
Temairazu: TEMAIRAZU intrusion[Intrusion][Data leak]Leaked 4.5MOrganizations 1Disclosed 2026-09-28Updated 2026-09-28Tokyo[Contained][Severity: Major]
Shueisha: HAPPY PLUS COMMUNITY intrusion[Misconfiguration][API abuse][Data leak]Leaked 2.8KOrganizations 1Disclosed 2026-09-27Updated 2026-10-02Tokyo[Contained][Severity: Critical]
Starts Publishing: OZmall intrusion[Web app exploit][Data leak]Leaked 447.6KOrganizations 1Disclosed 2026-09-27Updated 2026-09-27Tokyo[Investigating][Severity: Major]
Tokyo Metro: Metpo intrusion[Intrusion][Data leak]Leaked 59KOrganizations 1Disclosed 2026-09-26Updated 2026-10-30Tokyo[Investigating][Severity: Critical]
Keio: ransomware attack on the group[Ransomware][Service outage][Extortion]Organizations 1Disclosed 2026-09-26Updated 2026-09-29Tokyo[Investigating][Severity: Major]
Nippon Rent-A-Car: unauthorized access to its app[Unknown][Data leak]Leaked 41Organizations 1Disclosed 2026-09-25Updated 2026-10-23Tokyo[Contained][Severity: Critical]
Times Mobility: Times Car data leak[Web app exploit][Data leak]Leaked 6.6MOrganizations 1Disclosed 2026-09-25Updated 2026-10-16Tokyo[Contained][Severity: Major]
Japan Post: intrusion into its international mail inquiry service[Intrusion][Data leak]Leaked 600Organizations 1Disclosed 2026-09-25Updated 2026-09-25Tokyo[Investigating][Severity: Critical]
Fines: unauthorized access to its booking system[Intrusion][Data leak]Leaked 1.5MOrganizations 1Disclosed 2026-09-20Updated 2026-10-14 08:05Tokyo[Contained][Severity: Moderate]
GMO Internet: malicious programs planted on ConoHa WING[Intrusion][Malware]Organizations 1Disclosed 2026-09-17Updated 2026-10-27Tokyo[Investigating][Severity: Moderate]
Asahi Kasei: former employee passes trade secrets to China[Insider][Data leak]Organizations 1Disclosed 2026-09-16Updated 2026-11-01 13:58Tokyo[Contained][Severity: Major]
GMO GlobalSign: GMO Trust Login customer files open to outside retrieval[Misconfiguration][Data leak]Leaked 45KOrganizations 1Disclosed 2026-09-15Updated 2026-09-15Tokyo[Contained][Severity: Critical]
LEAN BODY: unauthorized access to its data analysis tool[Web app exploit][Data leak]Leaked 440KOrganizations 1Disclosed 2026-09-11Updated 2026-09-12Tokyo[Contained][Severity: Critical]
Digital Agency: Government Solution Service intrusion[Intrusion][Data leak]Leaked 246KOrganizations 1Disclosed 2026-09-09Updated 2026-09-30Tokyo[Contained][Severity: Critical]
ApplyNow: unauthorized access to its recruiting platform[Web app exploit][Data leak]Leaked 390KOrganizations 2Disclosed 2026-09-08Updated 2026-09-11 08:00Tokyo[Contained][Severity: Moderate]
Rikkyo University: student and alumni Google account intrusion[Intrusion]Organizations 1Disclosed 2026-09-07Updated 2026-09-08Tokyo[Investigating][Severity: Major]
Institute of Science Tokyo: IT infrastructure intrusion[Intrusion][Data leak]Organizations 1Disclosed 2026-09-02Updated 2026-09-03Tokyo[Contained][Severity: Critical]
RIZAP: health guidance data uploaded to external AI[Insider][Data leak]Leaked 20KOrganizations 3Disclosed 2026-09-02Updated 2026-09-02Tokyo[Resolved][Severity: Critical]
Seibu Railway: 52 Seats of Happiness bookings exposed[Misconfiguration][Data leak]Leaked 500Organizations 1Disclosed 2026-09-01Updated 2026-09-28Tokyo[Contained][Severity: Major]
Mitsui Fudosan: group system intrusion[Credential abuse][Data leak]Leaked 36KOrganizations 1Disclosed 2026-08-31Updated 2026-09-01Tokyo[Contained][Severity: Major]
Ando Hazama: police impersonation scam[Phishing][Data leak]Leaked 5KOrganizations 1Disclosed 2026-08-30Updated 2026-09-01Tokyo[Contained][Severity: Major]
Mandarake: unauthorized access to its servers[Intrusion][Data leak][Service outage]Organizations 1Disclosed 2026-08-28Updated 2026-10-15Tokyo[Contained][Severity: Critical]
Yellow Hat: online service booking system intrusion[Web app exploit][Data leak][Service outage]Leaked 1.8MOrganizations 1Disclosed 2026-08-27Updated 2026-08-28Tokyo[Investigating][Severity: Major]
Zurich: Z-Dash intrusion[Web app exploit][Data leak]Leaked 1.7KOrganizations 1Disclosed 2026-08-25Updated 2026-08-25Tokyo[Contained][Severity: Major]
Cover: hololive OFFICIAL CARD GAME intrusion[Web app exploit][Data leak]Organizations 1Disclosed 2026-08-24Updated 2026-10-16Tokyo[Contained][Severity: Critical]
All Nippon Airways Trading: Eraberu e-GIFT intrusion[Intrusion][Data leak][Fraud][Service outage]Organizations 1Disclosed 2026-08-24Updated 2026-08-25Tokyo[Contained][Severity: Critical]
Fancrew: mystery shopper service credential stuffing[Credential abuse][Data leak][Fraud][Service outage]Leaked 59.4KOrganizations 1Disclosed 2026-08-21Updated 2026-08-28Tokyo[Contained][Severity: Major]
Rakuten Books Network: work PC intrusion[Intrusion][Data leak]Leaked 33.3KOrganizations 2Disclosed 2026-08-18Updated 2026-08-28Tokyo[Contained][Severity: Moderate]
Weblife: intrusion into the customer system of its OEM website-building service[Web app exploit][Data leak]Leaked 7.4KOrganizations 1Disclosed 2026-08-18Updated 2026-08-21Tokyo[Contained][Severity: Critical]
VOISING: unauthorized access to a BI tool it uses[Web app exploit][Data leak]Leaked 170KOrganizations 1Disclosed 2026-08-14Updated 2026-08-17Kanagawa, Tokyo[Contained][Severity: Major]
T museum: Unko Museum website tampered with[Web app exploit][Data leak][Site defacement]Leaked 4Organizations 2Disclosed 2026-08-13Updated 2026-08-13Tokyo[Investigating][Severity: Moderate]
Tokyo Gas Network: work laptop lost[Lost device][Data leak]Leaked 20KOrganizations 1Disclosed 2026-08-12Updated 2026-10-05Tokyo[Contained][Severity: Critical]
White Essence: booking site and core system intrusion[Web app exploit][Data leak][Service outage]Leaked 1.1MOrganizations 1Disclosed 2026-08-10Updated 2026-10-09Tokyo[Resolved][Severity: Critical]
REXT: ransomware on the headquarters and store network[Ransomware][Data leak][Service outage]Leaked 1MOrganizations 2Disclosed 2026-08-10Updated 2026-08-12Tokyo[Investigating][Severity: Critical]
RIZAP: unauthorized access to the APORITO online store[Web app exploit][Data leak][Service outage]Organizations 1Disclosed 2026-08-06Updated 2026-10-20Tokyo[Contained][Severity: Critical]
Ambition DX Holdings: ransomware attack[Ransomware][Intrusion][Data leak]Leaked 580KOrganizations 1Disclosed 2026-08-05Updated 2026-08-05Tokyo[Investigating][Severity: Major]
Kyodo News: staff accounts misused[Credential abuse][Data leak]Leaked 6KOrganizations 1Disclosed 2026-08-04Updated 2026-08-10Tokyo[Contained][Severity: Major]
Innovation: unauthorized access to its GitHub[Credential abuse][Data leak]Leaked 62.7KOrganizations 1Disclosed 2026-08-03Updated 2026-08-24 08:05Tokyo[Resolved][Severity: Critical]
Toshiba Tec: ShopCraft data exposure[Misconfiguration][Data leak]Leaked 382.1KOrganizations 1Disclosed 2026-08-03Updated 2026-08-03Tokyo[Contained][Severity: Major]
Kodansha: unauthorized access to a company email account[Phishing][Credential abuse][Data leak]Leaked 3.8KOrganizations 1Disclosed 2026-08-01Updated 2026-10-16Ishikawa, Tokyo[Contained][Severity: Critical]
Estore: shopper data leaked from ShopServe[Web app exploit][Data leak]Leaked 23.4MOrganizations 2Disclosed 2026-07-31Updated 2026-09-24Tokyo[Contained][Severity: Critical]
EPARK Relax & Esthe: PeakManager intrusion[Credential abuse][Data leak]Leaked 33MOrganizations 1Disclosed 2026-07-29Updated 2026-09-14Tokyo[Contained][Severity: Major]
Life Insurance Association: policy inquiry system data exposure[Misconfiguration][Data leak][Service outage]Leaked 37.9KOrganizations 1Disclosed 2026-07-29Updated 2026-08-18 08:05Tokyo[Contained][Severity: Critical]
C-Connect: Ink Kakumei payment system tampering[Web app exploit][Data leak][Fraud]Leaked 24.2KOrganizations 1Disclosed 2026-07-27Updated 2026-08-13 08:05Tokyo[Contained][Severity: Critical]
Fine: online shop server hack and tampering[Web app exploit][Data leak]Leaked 912Organizations 1Disclosed 2026-07-24Updated 2026-09-17Tokyo[Contained][Severity: Critical]
murauchi.com: unauthorized access[Web app exploit][Data leak][Service outage]Leaked 7.7MOrganizations 1