Summary
- Environment: Quanum LSM test-order and results system
- Operational impact: Quest reported no material business or patient-service disruption
- Financial impact: No quantified incident cost disclosed
- Record status: Developing record. Reviewed October 22, 2026; updated as evidence emerges.
What happened
Quest Diagnostics learned of unauthorized access to Quanum LSM on October 21, 2026. Certain clients use the system for test orders and results. [1]
Impact
Quest believed some patient records were accessed, but had not established the full scope. It reported no material disruption to operations or patient services. No affected-patient count or detailed data categories were disclosed. [1]
Timeline
Unauthorized access discovered
The discovery date does not establish when the intrusion began.
[1]SEC disclosure filed
Quest described the incident in Form 8-K, Item 8.01.
[1]Briefing updated
This briefing was last reviewed and updated on October 22, 2026.
Threat Group & Attack Vector
The initial access method and attacker identity were not disclosed in the filing.
Actors
- No threat actor group has been identified in the reviewed public evidence.
TTPs
- No specific MITRE ATT&CK technique is currently mapped for this case.
Response
Quest initiated containment, investigation and remediation, engaged external cybersecurity experts and notified federal law enforcement. The investigation remained ongoing. [1]