HackingHealthcareHealthcareSupply Chain (3P Vendor)Business Associate (HIPAA)Customer Data InvolvedDelayed DiscoveryHealth (basic)Identity (basic)Government IDPHIMediumContained

Johnson Memorial Health System

bd_b1d1cab49068bd71 · schema v1 · pii pii-v2

Severity

Medium

Discovered

—

Filed

Sep 1, 2026

To disclose

—

Affected

3state residents only

Confidence

69%

Full breach record for Johnson Memorial Health System →

Johnson Memorial Health System notified patients of a data breach involving their protected health information (PHI). The incident occurred at Aesto, LLC, a third-party vendor providing healthcare data migration and archiving services. An unauthorized actor accessed PHI stored on Aesto's AWS infrastructure between December 2 and December 18, 2025. Aesto discovered the incident on December 18, 2025. The affected data includes full names and other health information. Johnson Memorial Health System is offering complimentary credit monitoring to affected individuals.

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Incident timeline

Dec 2, 2025

Begins

Sep 1, 2026

Filed

Tracked as a single-filing incident — the only disclosure on record for this event so far.Confirmed3 affectedView incident

Name: Johnson Memorial Health System
norm: johnson memorial health system

Name: Johnson Memorial Health System
norm: johnson memorial health system
Industry: Healthcarellm

Discovered: —
Breach occurred: Dec 2, 2025 – Dec 18, 2025
Materiality determined: —
Notification sent: —
Affected individuals: 3state-resident count only
Data types: Health (basic)Identity (basic)Government IDPHI
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Third party: via Aesto, LLC

During the incident: Commenced a prompt and thorough investigation
Worked very closely with external cybersecurity professionals experienced in handling these types of incidents
Conducted extensive forensic investigation and manual document review
Offering a complimentary membership of Experian IdentityWorks Credit 3B
Source: Quoted from the filing itself, not independently verified.

Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://www.mass.gov/doc/2026-1508-johnson-memorial-health-system/download
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Sep 1, 2026
Raw hash: 691b6c2338034a85a313b721b22a0f2b76a4d97f6d1ee4eddcbe5f717fb1a110

Reporting entityJohnson Memorial Health System

Victim entityJohnson Memorial Health System

IncidentUnauthorized Access

Stated responseCommenced a prompt and thorough investigation

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov