Quest Diagnostics (Quanum LSM) Data Breach
On October 21, 2026, U.S. clinical laboratory operator Quest Diagnostics (questdiagnostics.com) identified unauthorized activity targeting its Quanum Lab Services Manager (LSM), an online portal used by healthcare providers and hospitals to place laboratory orders and look up patient test results.
The organization has not published how many were affected, so the incident cannot be placed on this scale.
Exposed Data Types
3 sensitive4- Patient IDs
- Medical records
- Protected health information
- Names
About This Breach
Disclosed in a Form 8-K filing with the U.S. Securities and Exchange Commission (SEC) on October 22, 2026, the incident prompted Quest to temporarily suspend access to the Quanum LSM platform.
Quest Diagnostics stated that an unauthorized party likely accessed patient records and personal health information, while the exact categories of compromised data and total number of affected individuals remained under forensic investigation with external experts and law enforcement.
Verification and editorial method
LeakData compares the incident name, date, affected-record count, and exposed data types with accessible sources. Unverified fields are not presented as facts, and records are updated when new evidence becomes available.
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