John Muir Health - Walnut Creek Medical Center
Disclosed Apr 13, 20233 years ago821 affectedConfirmed
The covered entity (CE), John Muir Health – Walnut Creek Medical Center, reported that a workforce member posted a link to protected health information (PHI) on a publicly accessible website. This breach affected the PHI of 821 individuals. The PHI involved included names, diagnoses, and other treatment information. The CE notified HHS, affected individuals, the media, and provided substitute notice. In response to the breach, the CE sanctioned the workforce member involved and implemented additional administrative, technical, and security safeguards. Staff members were retrained to better protect its PHI.
What is known
| People affected | 821 (as reported to HHS) |
|---|---|
| Disclosed | Apr 13, 2023 |
| Happened | Jul 1, 2021 |
| Attack | Insider |
| Data exposed | Names, Health |
| Sector | Healthcare · US |
| Status | Confirmed |
Sources
| Source | |
|---|---|
| California Attorney General breach notice: John Muir Health - Walnut Creek Medical Centeroag.ca.gov · Official notice | Official notice |
| HHS OCR breach report (archive, resolved): John Muir Health - Walnut Creek Medical Center (Healthcare Provider, CA)ocrportal.hhs.gov · Official notice | Official notice |
Notices filed
| Where | Filed | People |
|---|---|---|
| California AGresidents of CA | Apr 13, 2023 | |
| HHS archivetotal | Apr 13, 2023 | 821 |
History of this record
- 2026-09-25 · attack: unknown to insider · backfill source
- 2026-09-25 · data_types: [] to ["names","health"] · backfill source
- 2026-09-25 · records_basis: empty to hhs · backfill source
- 2026-09-25 · records: empty to 821 · backfill source
- 2026-09-25 · summary: empty to The covered entity (CE), John Muir Health – Walnut Creek Medical Center, reported that a workforce member posted a link to protected health information (PHI) on a publicly accessible website. This breach affected the PHI of 821 individuals. · backfill source
- 2026-09-25 · added · backfill source
First seen 2026-09-25 (California AG), confirmed by California AG. Record counts are as reported. Not legal advice.
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