People search Quest Diagnostics data breach timeline because regulated data and trust are existential—one incident triggers class actions and regulator exams. BreachHistory indexes 5 Quest Diagnostics-linked incidents, with headline counts up to 20M+ in catalog rows. This page maps every attested event through 2026 with internal links to canonical records.
Why Quest Diagnostics breach history matters
Quest Diagnostics operates in Healthcare (United States). Across indexed rows, recurring themes include cloud and database misconfiguration. Understanding the chronological pattern helps security teams, customers, and regulators separate confirmed disclosures from forum marketing.
Full timeline through 2026
2019 — — Quest Diagnostics: One of the biggest blood testing providers in the…
Cataloged incident. June 2019. One of the biggest blood testing providers in the United States leaked personal, financial and medical information due to a security issue with one of its vendors. BreachHistory cites approximately 11.9M+ affected records in this row. See the quest-diagnostics2019 and canonical BreachHistory entry.
2019 — — Quest Diagnostics: Poor security / misconfiguration, 20,000,000 records
Cataloged incident. For an 8 month period, a hacker group stole personal and payment information from a firm providing billing services for the US healthcare sector. Exposed categories include Personal and demographic data. BreachHistory cites approximately 20M+ affected records in this row. See the quest-diagnostics2019-iib and canonical BreachHistory entry.
2016 — — Quest Diagnostics: Quest Diagnostics regrets to notify you of a breach…
Cataloged incident. Quest Diagnostics regrets to notify you of a breach of your Protected Health Information (PHI) which we became aware of on November 28, 2016. Here are the details of the breach: On November 26th an unauthorized third party accessed the MyQuest by Care360® internet application and obtained PHI of approximately 34,000 patients. The data included name, date of birth, lab results, and, in some instances, telephone numbers. The affected information did not include Social Security numbers, credit ca Exposed categories include Personal information. BreachHistory cites approximately 34K+ affected records in this row. See the quest-diagnostics2016 and canonical BreachHistory entry.
2016 — — Quest Diagnostics: Nov, 34K records
Cataloged incident. Nov. The stolen data contained names, DOBs, lab results and some telephone numbers. BreachHistory cites approximately 34K+ affected records in this row. See the quest-diagnosticsu and canonical BreachHistory entry.
2012 — — Quest Diagnostics: A dishonest employee was discovered to have…
Cataloged incident. A dishonest employee was discovered to have forwarded emails that contained sensitive personal information in late July. The emails included names, Social Security numbers, addresses, dates of birth, driver's license numbers, financial account information, and medical/health insurance information. Exposed categories include Personal information. No attested victim count is published for this row yet. See the quest-diagnostics2012 and canonical BreachHistory entry.
Patterns and analysis
- Cloud and database misconfiguration — appears across multiple Quest Diagnostics catalog entries; prioritize controls that address this class of failure.
- Record-count hygiene — BreachHistory indexes actor-cited figures separately from company-confirmed totals; read each row's technicalWriteup before treating counts as fact.
- 2026 monitoring — New disclosures roll into this timeline as they are verified or labeled unverified per catalog policy.
What to do if you may be affected
- Step 1: Enable phishing-resistant MFA on every account tied to this brand.
- Step 2: Use unique passwords and a password manager—breach rows often involve credential reuse.
- Step 3: Monitor official company breach notices and regulator filings, not dark-web downloads.
- Step 4: Watch for medical-ID theft and billing fraud after health-data incidents.
- Step 5: Bookmark the Quest Diagnostics company page for new 2026+ disclosures.
Canonical BreachHistory hub
Explore every indexed row: breachhistory.com/quest-diagnostics · Latest: quest-diagnostics2019.
Sources: BreachHistory catalog (5 rows for Quest Diagnostics), company and regulator disclosures cited in individual breach records.