MedStar Health Data Breach Impacts 64k: Sensitive PII and PHI Exposed

On Oct. 4, 2025, MedStar Health, the largest healthcare provider in Maryland and the Washington, D.C., region, discovered a cybersecurity incident affecting its systems. The incident impacted a total of 64,332 individuals across the nation.

According to the company’s official data incident notice, an unauthorized party gained access to MedStar Health’s networks between Sept. 12 and Sept. 16, 2025.

The breach was linked to a ransomware attack by the RHYSIDA group, which claimed responsibility on the dark web and threatened to publish stolen data within a week of the incident.

The files accessed during this period contained both personally identifiable information (PII) and protected health information (PHI) of current and former patients, including patients’ names, dates of birth, Social Security numbers, and potentially other protected health information such as diagnoses, medications, test results, images, health insurance details and treatment information.

MedStar Health began notifying affected patients by mail on Dec. 3, 2025.

MedStar Health's response

Individuals who receive a notification letter from Medstar Health about the incident may want to:

• Sign up for the free identity theft protection services, if offered by Medstar Health.
• Monitor your credit reports and financial accounts for any unusual activity.
• Be alert for phishing emails or phone calls that may use your exposed information.
• Consider placing a fraud alert or credit freeze with major credit bureaus.

To support affected individuals, MedStar Health has established a dedicated, toll-free call center at 855-403-1763, available Monday through Friday, 9 a.m. to 9 p.m. ET, except holidays.