California · State rollup
Healthcare data breaches in California, 2026.
50 HHS OCR-reported healthcare data breaches affecting 15.6M California residents. 10 attributed to ransomware groups. Each entry below names the provider, the data exposed, and the steps to take if you received a notification letter.
Date Type Organization Affected
Unauthorized access City Health, a medical corporation 65,000 Unauthorized access Ouster, Inc. 574 Hacking CardioFit Medical Group, Inc. 7,243 Hacking Tieu Dental Corporation 8,918 Phishing Nephrology Associates Medical Group, Inc. 4,631 Hacking AltaMed Health Services Corporation 501 Hacking Marin Cancer Care 501 Phishing Personalis, Inc. 650 Ransomware Docs Medical Group, Inc. dba Pulse Urgent Care 4,035 Vendor breach North East Medical Services 91,513 Hacking Pit River Health Service Inc. 1,800 Hacking Centric Health 6,855 Ransomware Cerenade 987 Ransomware Archer Health 4,285 Ransomware Beverly Hills Oncology Medical Group 57,655 Ransomware Expert MRI 209,560 Hacking Michael R. Schwartz, MD Inc. 9,809 Hacking Valley Radiology 1,166 Hacking Reimagine Network 4,799 Hacking Pacific Imaging Management, LLC 13,158 Hacking Welcome Dentistry-Anaheim 1,001 Hacking Welcome Dentistry-Los Angeles 1,001 Hacking Mission City Community Network, Inc. 11,016 Hacking Friesen Group 500 Hacking South Coast Pediatrics 7,000 Phishing California Cancer Associates for Research and Excellence – High Desert 17,250 Phishing California Cancer Associates for Research and Excellence – San Diego 638 Hacking Orange County Radiation Oncology Medical Group 1,911 Hacking Radiation Oncology Network of Southern California, LLC 12,944 Hacking Los Angeles County Developmental Services Fdn., Inc. dba Frank D. Lanterman Regional Center 19,000 Unauthorized access AltaMed Health Services Corporation 4,530 Hacking Imperial Beach Community Clinic 10,358 Misconfiguration Blue Shield of California 1,543 Ransomware Episource, LLC 6.7M Vendor breach Sharp Community Medical Group 26,976 Hacking Sharp HealthCare 500 Ransomware Berkeley Research Group, LLC 500 Hacking Palo Verde Hospital 594 Unauthorized access Icon Family Healthcare LLC 1,800 Hacking The City of Long Beach, CA 258,191 Phishing Altior Healthcare, LLC 1,002 Misconfiguration Blue Shield of California 4.7M Ransomware Dameron Hospital 210,706 Ransomware MedRevenu, LLC 17,775 Physical theft SCLARC 722 Hacking Kronick Moskovitz Tiedemann & Girard 2,511 Ransomware PIH Health, Inc. 2.9M Hacking Newport Harbor Pathology Medical Group 501 Hacking Newport Harbor Pathology Medical Group, Inc. 119,341 Hacking North Los Angeles County Regional Center 500