Memorial Hermann Health System notified thousands of its customers of the data breach after one of its contracted vendors, Advent Health Partners, suffered a cyber attack. Unauthorized access and suspicious activities were noticed on an employee's email accounts with data from Memorial Hermann including PHI: first names, last names, dates of birth, social security numbers, financial and medical information. All the impacted customers were notified and given free credit monitoring services.

The U.S. Department of Health and Human Services reported on August 29, 2014, that Memorial Hermann Health System experienced a data breach due to unauthorized access/disclosure on July 7, 2014, affecting approximately 10,604 individuals' protected health information (PHI). The incident involved a workforce member accessing the information inappropriately through a desktop computer, and corrective actions were taken post-incident, including the termination of the workforce member and the expansion of the IT audit program.