1st MidAmerica Credit Union Data Breach Investigation

Recently, 1st MidAmerica CU reported to the Attorney General of Maine that it had experienced a data breach in which sensitive personal identifiable information in its care may have been compromised. According to the breach notice, on or around August 14, 2025, 1st MidAmerica CU was informed by Marquis Software Solutions (“Marquis”), a vendor of 1st MidAmerica CU, that it had identified suspicious activity on its network and determined that the activity was the result of a cybersecurity incident.¹ As a result, Marquis launched an investigation to determine the nature of the incident.

Through its investigation, Marquis confirmed to 1st MidAmerica CU confirmed that sensitive personal information in Marquis systems related to 1st MidAmerica CU may have been accessed or acquired by an unauthorized third party during the breach. As a result, 1st MidAmerica CU began a review of the data to determine what information had been impacted as well as identify the specific individuals affected. While the information impacted varies depending on the individual, the type of information potentially exposed includes:

• Name
• Social Security number

As a result of the breach, Marquis began mailing data breach notification letters to impacted individuals on behalf of 1st MidAmerica CU. Based on the breach notice sent to Maine residents, 1st MidAmerica CU is providing affected individuals with a list of the specific types of sensitive information impacted and 24 months of complimentary credit monitoring services. A link to the form breach notification letters that 1st MidAmerica CU filed with the Attorney General of Maine is below.