---
title: "UMMC network-data incident"
description: "UMMC reported unauthorized network access in February 2026 and identified potentially affected personal and health information in October."
incident_type: "Cybersecurity incident"
status: "active"
last_modified: "2026-11-04"
canonical_url: "https://www.ally.security/incidents/ummc-network-data-incident-2026"
markdown_url: "https://www.ally.security/incidents/ummc-network-data-incident-2026.md"
stix_url: "https://www.ally.security/incidents/ummc-network-data-incident-2026/stix.json"
---

# UMMC network-data incident

The University of Mississippi Medical Center identified unauthorized network access around February 19, 2026.

Last modified Nov 4, 2026 · 1 source

## Summary

- **Environment:** Medical-center computer network
- **Operational impact:** Personal and protected health information potentially accessed or acquired
- **Financial impact:** No incident cost disclosed

## What happened

The [University of Mississippi Medical Center](https://www.umc.edu/) identified unauthorized network access around February 19, 2026. [1](#source-1)

## Impact

On October 20, UMMC concluded that files containing personal or protected health information may have been accessed or acquired between February 11 and February 19. [1](#source-1)

The public notification template specifies names but leaves recipient-specific data categories blank. It does not establish the complete set of exposed fields or a total affected population. [1](#source-1)

## Timeline

### February 11, 2026 — Reported access window begins

Reported access window begins, according to the published account. [Incident notice](https://oag.ca.gov/system/files/UMMC_Notice_Letter_Example_%28Redacted%29_40414800v1.pdf). [1](#source-1)

### February 19, 2026 — Reported access window ends

Reported access window ends, according to the published account. [Incident notice](https://oag.ca.gov/system/files/UMMC_Notice_Letter_Example_%28Redacted%29_40414800v1.pdf). [1](#source-1)

### October 20, 2026 — Potential data impact identified

Potential data impact identified, according to the published account. [Incident notice](https://oag.ca.gov/system/files/UMMC_Notice_Letter_Example_%28Redacted%29_40414800v1.pdf). [1](#source-1)

### November 4, 2026 — Briefing updated

This briefing was last reviewed and updated on November 4, 2026.

## Threat Group & Attack Vector

The reviewed notice does not establish the initial access method.

### Actors

- No threat actor group has been identified in the reviewed public evidence.

### TTPs

- No specific MITRE ATT\&CK technique is currently mapped for this case.

## Response

UMMC secured its systems, worked with outside cybersecurity specialists and offered identity monitoring. It reported no evidence of financial fraud or identity theft involving the information at notification. [1](#source-1)

## Assets

[Download the case-scoped STIX 2.1 bundle](<https://www.ally.security/incidents/ummc-network-data-incident-2026/stix.json>)

## Sources

Primary source records used to research this incident.

<a id="source-1"></a>

### University of Mississippi Medical Center notice of data security incident

official · University of Mississippi Medical Center

<https://oag.ca.gov/system/files/UMMC_Notice_Letter_Example_%28Redacted%29_40414800v1.pdf>

<details>
<summary>Evidence ledger</summary>

Review the supporting structured claims.

1. **Occurred At · 100% confidence · current**  
   Potential data impact identified: 2026-10-20
2. **Affected Organization · 100% confidence · current**  
   UMMC network-data incident: University of Mississippi Medical Center
3. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: Reported access window ends
4. **Occurred At · 100% confidence · current**  
   Reported access window begins: 2026-02-11
5. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: UMMC secured its systems, worked with outside cybersecurity specialists and offered identity monitoring. It reported no evidence of financial fraud or identity theft involving the information at notification.
6. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: Reported access window begins
7. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: Potential data impact identified
8. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: The public notification template specifies names but leaves recipient-specific data categories blank. It does not establish the complete set of exposed fields or a total affected population.
9. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: On October 20, UMMC concluded that files containing personal or protected health information may have been accessed or acquired between February 11 and February 19.
10. **Resulted In · 100% confidence · current**  
   UMMC network-data incident: The University of Mississippi Medical Center identified unauthorized network access around February 19, 2026.
11. **Occurred At · 100% confidence · current**  
   Reported access window ends: 2026-02-19

</details>