McKesson Data Breach Class Action Investigation

KANTROWITZ, GOLDHAMER, GRAIFMAN, PERLMUTTER & CARBALLO, P.C. is investigating potential claims against McKesson Corporation (“McKesson”) arising from a significant data breach involving highly sensitive patient and healthcare information.

McKesson is one of the largest healthcare companies in the United States and provides pharmaceutical distribution, prescription technology, medical-surgical, oncology, and other healthcare services.

On August 28, 2026, McKesson publicly disclosed that it had discovered a cybersecurity incident involving unauthorized access to third-party applications and the exfiltration of data. The cybercriminal group ShinyHunters has claimed responsibility for the attack and reportedly claims to have stolen approximately one terabyte of data, including approximately 284 million patient-related records. The precise number of individuals affected is not yet known.

The information reportedly compromised may include:

• Names, addresses, dates of birth, phone numbers, and email addresses;
• Social Security numbers;
• Patient identification and medical record numbers;
• Medicaid numbers;
• Diagnoses, illnesses, medications, allergies, and disabilities;
• Appointment and physician information;
• Prescription information;
• Billing and shipment information; and
• Other sensitive medical and healthcare information.

We are investigating whether McKesson failed to implement reasonable and appropriate cybersecurity safeguards to protect patient information and whether individuals whose personal and medical information was compromised are entitled to compensation.

If you are a current or former patient, customer, or other individual whose personal or medical information was maintained by or accessible to McKesson and you believe your information may have been affected by this data breach, you may have a claim. If you wish to discuss your rights or possible participation in a class action lawsuit, please contact class action attorneys Melissa R. Emert, Esq. or Gary S. Graifman, Esq. at:

Kantrowitz, Goldhamer, Graifman, Perlmutter & Carballo, P.C.
135 Chestnut Ridge Road – Suite 200
Montvale, NJ 07645
Phone: (866) 896-0935
Email: [email protected] or [email protected]