BETHALTO, Ill. — A data breach involving 1st MidAmerica Credit Union may have exposed sensitive personal information for more than 131,000 people, according to Strauss Borrelli PLLC.
The law firm said the incident traces back to an August 2025 cybersecurity compromise at Marquis Software Solutions, a third-party vendor used by the $1.4-billion-asset credit union. Strauss Borrelli PLLC reported that Marquis detected suspicious activity on its network around Aug. 14 and later confirmed that unauthorized actors likely accessed data connected to 1st MidAmerica members.
According to filings reviewed by Strauss Borrelli PLLC, the exposed information can include names and Social Security numbers, though the precise data varies by individual. Marquis has begun mailing breach-notification letters on behalf of the credit union and is offering affected consumers 24 months of free credit-monitoring services, the firm said.
The 1st MidAmerica incident is part of a growing wave of fallout from the Marquis breach, with multiple other financial institutions reporting similar impacts in recent months.