MAINSTREET FEDERAL CREDIT UNION

Mainstreet Federal Credit Union notified Massachusetts residents of a data security incident involving unauthorized access to customer information, likely via a phishing attack targeting the credit union's email environment. The incident compromised personal data, and the credit union has enhanced its email security measures.

Mainstreet Credit Union notified the NH Attorney General that an unauthorized actor accessed an employee's email account between January 12 and January 20, 2026. The investigation determined that the account contained the name and financial account number of one New Hampshire resident. The organization secured the account, engaged a forensic firm, and mailed notifications to the affected individual on June 18, 2026.

Mainstreet Credit Union reported a data breach to the Indiana Attorney General. The breach occurred on 2026-01-12 and was reported on 2026-05-04. 1 Indiana residents were affected. 4,123 individuals affected in total.

Mainstreet Credit Union reported unauthorized access to a single employee Microsoft 365 email account between January 12 and 20, 2026. The breach affected two Nebraska residents, exposing personal information including Social Security numbers and driver's license numbers. Notifications were mailed on May 4, 2026, offering 12 months of credit monitoring via Kroll.