Quest Diagnostics takes lab results system offline after unauthorized access

Past-week coverage · Original source published 2026-10-23.

Quest Diagnostics said a key system it uses to manage medical test results was taken offline after the company discovered unauthorized access, and warned that it believes some patient data in that system was accessed.

The platform, Quanum Lab Services Manager (LSM), is used to place test orders and to receive and look up results. Access was paused while Quest investigates. The company said no other part of Quest was affected, though several other systems were also paused during the probe. It said it is working with law enforcement and is still determining which patient data was involved.

Customers can use paper requisitions in place of the system, and Quest said it expected the platform to be back up by Friday. The company stated the incident did not involve the recent PHP vulnerabilities that have drawn concern among security experts. A Quest spokesperson declined to comment on the nature of the incident.

No hacking group had claimed responsibility as of Thursday afternoon. Quest is one of the largest clinical laboratory companies in the U.S. and says it serves half of the country's doctors and hospitals.

The disclosure follows other healthcare testing breaches this year, and Congress passed a bill this month expanding federal cyber requirements for healthcare organizations handling patient data.

For defenders at labs and other clinical data handlers, the practical questions are the ones Quest has not yet answered: what data sat in the affected system, how long access lasted, and whether identity or contact details were exposed alongside results. Organizations running similar order-and-results portals should confirm they can fall back to manual workflows, and should check logging and access controls on those systems rather than assume a vendor-side outage is contained.