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McKesson Data Breach Class Action Investigation

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Kantrowitz, Goldhamer, Graifman, Perlmutter & Carballo, P.C.

10b9db026d89119e951a851045ac17eee7784f79

Written/Reviewed By:

Barry S. Kantrowitz, Esq.

Last Updated: Sep 8, 2026

Read Time: 2 mins

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]

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   LWelsh 
 9 days ago
 
 
 Trustindex verifies that the original source of the review is Google. Clever and efficient.
  
 
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   Kenny Perlow 
 30 days ago
 
 
 Trustindex verifies that the original source of the review is Google. KGG Law, and Barry Kantrowitz in particular, set the bar high for what a thorough, practical, strategic, compassionate and smart lawyer can be. Everything about Barry's advice and representation was exemplary and the stress mitigation that resulted was invaluable. On top of that, the ultimate result Barry achieved was beyond what was reasonable to expect and we are forever grateful. Often, people say that you hire a lawyer to prevent a problem. Sometimes, unfortunately, you need an attorney to solve a problem and I could not recommend Barry and his firm any more highly in that regard.
  
 
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   Aliza Ali 
 94 days ago
 
 
 Trustindex verifies that the original source of the review is Google. My dad had a great experience with this law firm. From the very beginning, the team was professional, knowledgeable, and always willing to answer our questions. They kept us informed throughout the entire process and made what could have been a very stressful situation much easier to handle. We truly appreciated their dedication, honesty, and hard work. Thanks to their support, my dad felt confident every step of the way. We are very grateful for everything they did and would highly recommend this firm to anyone looking for reliable legal representation.
  
 
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   Jana Montero 
 97 days ago
 
 
 Trustindex verifies that the original source of the review is Google. I had a wonderful experience working with Sam Smith. He was very responsive, thorough, and easy to work with from start to finish. He walked me through everything clearly and made what started as a very stressful situation for me into something completely manageable. I would not hesitate to recommend him and the firm!
  
 
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   Mike Sakmann 
 103 days ago
 
 
 Trustindex verifies that the original source of the review is Google. I sought legal advice regarding an employment matter and had an excellent experience working with Sam Smith, Esq. at KGG Law. Sam was thorough, attentive, and took the time to listen carefully to my concerns before providing clear, thoughtful guidance. I appreciated the professionalism and care shown throughout the process, and I would confidently recommend KGG Law to anyone in need of legal assistance.
  
 
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   Liz Hecker 
 109 days ago
 
 
 Trustindex verifies that the original source of the review is Google. I can't say enough about this firm. They manage to comfort you during the whole legal process while staying professional and doing what is right. I would recommend them to anyone and also hire them again if I need legal help.
  
 
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 132 days ago
 
 
 Trustindex verifies that the original source of the review is Google. Kate is the best. She helped me very quickly, and was very attentive with all of my needs. So thankful for her
  
 
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   Mike Greenspan 
 145 days ago
 
 
 Trustindex verifies that the original source of the review is Google. Kate Carballo is a dedicated, passionate, and creative attorney whom I had the pleasure to lecture with at a state trial lawyer's conference. Kate's lecture demonstrated how she uses her innovative and "out-of-the-box thinking" to achieve outstanding results for her injured clients. That Kate is certified by the Supreme Court of New Jersey as a civil trial attorney is a testament to her skills, experience and commitment to excellence.
  
 
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   Jonathan Sampson 
 152 days ago
 
 
 Trustindex verifies that the original source of the review is Google. Was referred to KGG law by a friend and could not have asked for better legal representation. They walked me through every step of the process after my accident and began every call with “ how are you feeling” which was just one example of how much they care about their clients. They handled my case very efficiently, professionally and courteously. My attorney Kate Carballo was a rock star! So clearly experienced, she consistently made me feel at ease with the process. Highly recommend
  
 
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   Vinnie Kung 
 155 days ago
 
 
 Trustindex verifies that the original source of the review is Google. We had a great experience with the team at KGG Law. While it was a traumatic time for our family, they made it very easy for us and explained all of our options. They even performed due diligence to make sure that after our settlement, there would be no further issues which I think is even more important than the settlement itself. Thank you!

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McKesson Data Breach Class Action Investigation

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