Hackers Stole Data From Quest Lab System

Doctors and hospitals that rely on Quest Diagnostics' Quanum platform may face complications as the company confirms hackers accessed patient records. The incident affects the system used by roughly 500,000 clinicians in North America to order tests and process billing.

Quest Diagnostics disclosed the breach in an 8-K filing with the Securities and Exchange Commission. The company stated it became aware of the attack on Wednesday. The filing notes that unauthorized access included certain patient records, though Quest has not specified the volume of data taken.

A security notice on the company's website states that protected health information was stolen. This includes personal information and patient records. Quest is still determining the specific data types involved. The notice page currently contains noindex code, which prevents search engines from indexing the page and makes it difficult for patients to locate.

Quest has not revealed when the breach began or how many customers are affected. The company also has not confirmed whether a hacking group contacted it with ransom demands. Amanda Rivera, a Quest spokesperson, directed inquiries to the security notice rather than answering directly.

The potential scale of the exposure is large. Quest materials indicate that Quanum operates across thousands of locations. A 2026 case study on the company's website describes a single health system with over 6 million patients and hundreds of millions of related medical documents. It is unclear how many records the central system holds in total.

This incident adds to a series of cyberattacks on the healthcare sector in 2026. Previous breaches include a March attack on Stryker that wiped employee devices and an August hack at Boston Scientific that caused global disruption. Other victims this year include CareCloud, Craneware, and McKesson. These attacks typically involve financially motivated criminals who threaten to publish stolen data unless a ransom is paid.

This is Quest's second major data breach in ten years. In 2019, the company lost 11.9 million patient records following a cyberattack on a third-party billing company.