Quest Diagnostics says patient records were exposed in breach of its Quanum platform
Quanum has been taken offline and clinics are switching to paper requisitions or Quanum eLabs while the scope of the exposed data is still unknown.
Quest Diagnostics told US regulators in an SEC 8-K filing that it found unauthorised access to Quanum, the online platform clinics and hospitals use to order lab tests and retrieve results, and that some patient records were exposed. The company says it learned of the intrusion on October 21, 2026, and has brought in outside experts and notified law enforcement. Quanum has been taken offline, with customers pointed to paper requisitions or Quanum eLabs, while the types of data involved and the number of affected patients are still undetermined. Outside reporting says the platform serves about half a million clinicians, and this is Quest's second major breach in roughly a decade after the 2019 AMCA billing-provider incident exposed 11.9 million patient records. BleepingComputer said it could not find any threat group claiming responsibility as of its writing, a point that is not the same as confirming that no group has claimed it.
Why it matters
Quanum is used by about half a million clinicians across North America to order tests and retrieve results, so a breach of the platform reaches a wide group of patients whose records may have been exposed. Quest has not yet said which types of data were involved or how many patients were affected, which leaves those patients without a clear picture of their own risk. This is Quest's second major breach in about a decade, following the 2019 AMCA billing-provider incident that affected about 11.9 million patients, so the company's handling of the new incident will be watched against that history.
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