Quest Diagnostics Confirms Cyberattack on Quanum Lab Platform, Patient Records Exposed
An SEC filing says unauthorized access reached certain patient records; the company has not said how many people are affected.
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Quest Diagnostics has confirmed a cyberattack on its Quanum lab-testing platform that exposed sensitive patient information, TechCrunch reported on October 23, citing the company's disclosures.
What Quest disclosed
In an 8-K filing with the U.S. Securities and Exchange Commission, Quest said it learned of the attack on a Wednesday. Quanum lets doctors' offices, hospitals and other healthcare practices order lab tests for patients and manage billing. Quest said the unauthorized access included "certain patient records," that it notified law enforcement, and that an investigation is under way.
A notice on Quest's website said some patients' protected health information was taken, including "personal information and patient records." The company has not yet determined which specific types of data were stolen.
What is not known
- How many healthcare customers or patients are affected.
- When the breach began.
- Whether the attackers have made any ransom demand.
A Quest spokesperson referred reporters to the security notice rather than answering questions, TechCrunch said.
Scale and context
Quest says about half a million clinicians at thousands of locations across North America use Quanum. A 2026 Quest case study cited one health system with more than 6 million patients that holds hundreds of millions of medical documents.
TechCrunch noted that this is Quest's second known major breach in a decade; a 2019 attack on a third-party billing company exposed 11.9 million patient records. It also listed other 2026 healthcare cyber incidents, including attacks on Stryker in March and Boston Scientific in August.
