Quest Diagnostics halts lab system after data breach

Quest Diagnostics announced that one of its in‑house lab management systems, the Quanum Lab Services Manager, had been accessed by an unknown party. The company first learned of the breach on October 21, 2026 and immediately stopped access to the platform.

Discovery and immediate actions

Discovery and immediate actions: Quest Diagnostics paused the Quanum LSM system as soon as the intrusion was identified. The platform is used by a subset of clients to place test orders and view results, but the pause does not affect other ordering channels.

Investigation and response: The company activated its cyber‑incident response team, contained the breach, and is working with external cybersecurity experts and federal law‑enforcement agencies to determine the scope.

Impact on operations: Core Quest services remain operational. Other interfaces, such as electronic medical‑record and laboratory‑information‑system portals, are unaffected. Clients can place orders on paper or via fax while the system is restored, with a backup expected online by Friday.

Historical context: Quest has dealt with previous breaches in 2016 and 2019 that exposed lab results and personal information. The current incident is unrelated to recent PHP‑related vulnerabilities that have affected other organizations.

Ongoing status: Quest continues its investigation and will notify patients as required by law. The company has not yet provided a timeline for full restoration, and no threat actor has claimed responsibility.