BreachCensus

Quest Diagnostics Incorporated

United States of America

Quest Diagnostics Incorporated is an organisation in Massachusetts. It appears on the Massachusetts Attorney General breach-notification register with 2 confirmed incidents; the most recent notice was filed on October 25, 2024.

Data as of October 23, 2026.

Sources

Confirmed incident

US-MA

Disclosed
October 25, 2024

Timeline

  1. October 25, 2024
    Reported to regulator Regulator

    MA AG breach notification: 24 Massachusetts residents affected

    source
  2. October 21, 2026
    Press coverage Press

    press report (acknowledged): the unauthorized access was first identified on October 21, 2026

    source
  3. October 22, 2026
    Press coverage Press

    press report (press_reported): In its October 22, 2026, Form 8-K filing, the company said

    source
  4. October 22, 2026
    Press coverage Press

    press report (acknowledged): A key system used by Quest Diagnostics to manage medical test results was taken offline on Thursday after the company discovered unauthorized access.

    source
  5. Undated
    Press coverage Press

    press report (acknowledged): Quest Diagnostics said it learned of a cyber breach of one of its systems this week

    source
  6. Undated
    Press coverage Press

    press report (individuals_notified): The company said it discovered the hack on Wednesday and notified federal law enforcement.

    source
What a Massachusetts notice means

Governed by M.G.L. c. 93H. Notice to the Attorney General is required for a breach affecting any number of Massachusetts residents' personal information -- the statute sets no minimum count.

Note: the count is Massachusetts residents only, not a total.

Massachusetts breach-notification register ↗

Confirmed incident

US-MA

Disclosed
July 16, 2019

Timeline

  1. July 16, 2019
    Reported to regulator Regulator

    MA AG breach notification: 123,978 Massachusetts residents affected

    source

Litigation

  • Possible litigation — multiple candidate dockets found, not yet resolved to a single case.

Related

Disclosed around the same time