Leaked SquareML key exposed 238,083 Denver Health Plan members

An access key for a database held by analytics vendor SquareML was published online for roughly 14 months, exposing data on 238,083 current and former members of Denver Health Medical Plan (DHMP). DHMP disclosed the incident and reported it to the U.S. Department of Health and Human Services, as detailed by SecurityWeek. The key granted a read-only account, and DHMP says it has no evidence anyone used it.

What leaked and for how long

SquareML runs a no-code AI/ML analytics platform for healthcare. DHMP — a non-profit managed-care organisation inside the Denver Health and Hospital Authority, whose Medicaid Choice plan administers Health First Colorado benefits across Denver and three surrounding counties — fed member data into a SquareML database.

Per DHMP's notice, the timeline is the story:

• 27 June 2025 — the access key was published on a publicly accessible website.
• 14 August 2026 — SquareML notified DHMP the key had been inadvertently leaked.
• 18 August 2026 — the key was revoked.

That is roughly 14 months in which anyone who found the key could reach the database. Exposed fields include names, dates of birth, city/state/ZIP, demographic data, health metrics, health-plan eligibility data, provider name, and hospital admission, discharge, and transfer data. DHMP says the database held no Social Security numbers and no financial information.

Exploitation status

DHMP states the compromised account was read-only — it could not download, export, delete, or alter records — and that it has "no evidence that member information was viewed or misused, only that it may have been." Passwords for all accounts with access to the database were reset. Neither DHMP nor SquareML has said how the leak was discovered or where the key was posted. No attacker is named; this is an exposure, not a claimed intrusion.

Action checklist

1. DHMP members: watch Explanation-of-Benefits statements and medical records for care you did not receive; medical-identity misuse is the realistic risk here, not card fraud (no financial data was in scope).
2. If you run vendor-analytics pipelines: scan your own and your vendors' public repos, buckets, and sites for live credentials — this started with a key on a public page, not an intrusion.
3. Scope third-party keys to least privilege and rotate on a schedule; a read-only key limited the blast radius here, and a 14-month lifetime enlarged it.
4. Require breach-notification SLAs from analytics vendors — the gap between exposure (June 2025) and notice (August 2026) is the part DHMP could not control.

Context

The read-only scope is the only thing that kept this from being far worse, and it is a design choice more health plans should copy for vendor analytics. The recurring failure is credential hygiene at the processor, not the covered entity: a leaked key on a public page has now become one of the more common root causes in healthcare breach notices, ahead of the ransomware headlines.