Every public data breach

44 disclosed this week · 26,355 on record

Cornerstone Healthcare Group Management Services

Disclosed Mar 14, 2024484,957 affectedConfirmed

Official notice

Cornerstone Healthcare Group Management Services, the business associate (BA), reported that it experienced a hacking incident that compromised the protected health information (PHI) of 484,957 individuals. The PHI involved included names, addresses, dates of birth, Social Security numbers, drivers’ license numbers, financial information, health insurance information and clinical information. The notified HHS, the affected individuals, and the media. In response to the breach, the BA strengthened its technical safeguards. OCR provided technical assistance to the BA pertaining to the HIPAA Breach Notification and Security Rules.

What is known

People affected484,957 (as reported to HHS)
DisclosedMar 14, 2024
HappenedDec 19, 2023
AttackHacking
Data exposedNamesHealth
SectorHealthcare · US
StatusConfirmed

Sources

Notices filed

History of this record
attack2026-09-25
unknown to hackingby backfillSource
data_types2026-09-25
[] to ["names","health"]by backfillSource
records_basis2026-09-25
empty to hhsby backfillSource
records2026-09-25
empty to 484957by backfillSource
disclosed2026-09-25
2024-07-01 to 2024-03-14by backfillSource
summary2026-09-25
empty to Cornerstone Healthcare Group Management Services, the business associate (BA), reported that it experienced a hacking incident that compromised the protected health information (PHI) of 484,957 individuals. The PHI involved included names, by backfillSource
source2026-09-25
empty to https://ago.vermont.gov/document/2024-07-01-cornerstone-healthcare-group-management-services-data-breach-notice-consumersby backfillSource
disclosed2026-09-25
2024-11-01 to 2024-07-01by backfillSource
disclosed2026-09-25
2024-11-02 to 2024-11-01by backfillSource
Added2026-09-25
First recordedby backfillSource

First seen 2026-09-25 (California AG), confirmed by California AG. Record counts are as reported. Not legal advice.

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