---
title: "Quest Diagnostics Quanum LSM unauthorized access"
description: "Quest Diagnostics disclosed unauthorized access to Quanum LSM and believed certain patient records were accessed; the scope remained under investigation."
incident_type: "Cybersecurity incident"
status: "active"
last_modified: "2026-10-22"
canonical_url: "https://www.ally.security/incidents/quest-diagnostics-quanum-lsm-incident-2026"
markdown_url: "https://www.ally.security/incidents/quest-diagnostics-quanum-lsm-incident-2026.md"
stix_url: "https://www.ally.security/incidents/quest-diagnostics-quanum-lsm-incident-2026/stix.json"
---

# Quest Diagnostics Quanum LSM unauthorized access

Quest discovered unauthorized access to a client lab-services system on October 21, 2026 and disclosed it in an SEC filing the following day.

Last modified Oct 22, 2026 · 1 source

## 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

## What happened

[Quest Diagnostics](https://www.questdiagnostics.com/) learned of unauthorized access to Quanum LSM on October 21, 2026. Certain clients use the system for test orders and results. [1](#source-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](#source-1)

## Timeline

### October 21, 2026 — Unauthorized access discovered

The discovery date does not establish when the intrusion began. [1](#source-1)

### October 22, 2026 — SEC disclosure filed

Quest described the incident in [Form 8-K, Item 8.01](https://www.sec.gov/Archives/edgar/data/1022079/000094787126000941/ss6979200_8k.htm). [1](#source-1)

### October 22, 2026 — 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](#source-1)

## Assets

[Download the case-scoped STIX 2.1 bundle](<https://www.ally.security/incidents/quest-diagnostics-quanum-lsm-incident-2026/stix.json>)

## Sources

Primary source records used to research this incident.

<a id="source-1"></a>

### Quest Diagnostics Form 8-K — Quanum LSM unauthorized access

regulatory · Quest Diagnostics · Oct 22, 2026

<https://www.sec.gov/Archives/edgar/data/1022079/000094787126000941/ss6979200_8k.htm>

<details>
<summary>Evidence ledger</summary>

Review the supporting structured claims.

1. **Resulted In · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: Quest learned of unauthorized access to Quanum LSM, a system certain clients use to place test orders and receive or look up results.
2. **Discovered At · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: 2026-10-21
3. **Disclosed At · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: 2026-10-22
4. **Resulted In · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: Quest initiated containment, investigation and remediation procedures, notified federal law enforcement and engaged external cybersecurity experts.
5. **Resulted In · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: Quest said the incident had not materially disrupted business operations or its ability to serve patients.
6. **Resulted In · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: Quest said it believed an unauthorized party accessed certain patient records; the full scope remained under investigation.
7. **Affected Organization · 100% confidence · current**  
   Quest Diagnostics Quanum LSM unauthorized access: Quest Diagnostics

</details>