A data breach at Yale New Haven Health has exposed personal information of around 5.6 million people, marking the largest healthcare breach reported in 2025. Despite the breach, the health system’s medical record system and patient portal remained functional. Exposed data included demographic information, Social Security numbers, and medical records, although financial or employee data were not compromised.
Yale New Haven Health data breach affected over 5.5M people
Over 5.5 million people were affected by a data breach involving an “unauthorized third party” on Yale New Haven Health’s network (YNHHS) on March 8.
