Summary
- Environment: Healthcare-provider network
- Operational impact: Certain systems taken offline during response
- Financial impact: No confirmed incident cost quantified
- Record status: Developing record. Reviewed November 13, 2026; updated as evidence emerges.
What happened
Call-on-Doc detected unauthorized access December 28, 2025. Investigators later determined patient information may have been accessed or acquired between December 22 and January 3, 2026. [1]
Impact
Potential data included contact details, diagnoses, medication information and visit types, varying by patient. [1] The HHS OCR register lists 648,535 affected individuals for Call-on-Doc, with a September 18, 2026 submission. [2]
Timeline
Unauthorized access detected
Call-on-Doc took certain systems offline.
[1]Potential patient-data impact determined
The investigation established the possible access interval.
[1]Patient notification begins
The public notice described the incident and data categories.
[1]Briefing updated
This briefing was last reviewed and updated on November 13, 2026.
Threat Group & Attack Vector
The notice does not establish the entry method or confirm data exfiltration.
Actors
- No threat actor group has been identified in the reviewed public evidence.
TTPs
- No specific ATT&CK technique is mapped from the available evidence.
Response
Call-on-Doc used outside investigators, notified patients and said it was enhancing security practices. It reported no indication of related fraud. [1]