Marquis Breach Tally Climbs To 672,075 / Fresh Today / CUToday.info | #hacking | #cybersecurity | #infosec | #comptia | #pentest | #ransomware

PLANO, Texas— Marquis Software Solutions, a Plano-based fintech vendor whose 2025 ransomware attack has impacted numerous credit unions, has now disclosed that the incident affected 672,075 individuals, sharply expanding the known scope of one of the most significant third-party vendor breaches to hit the financial-services sector in the past year.

Marquis, which says it serves more than 700 banks and credit unions, had previously disclosed that the August 2025 attack affected at least 74 banks, credit unions and other financial institutions, but did not initially provide a total victim count. In updated breach notices and regulatory filings cited in reporting last week, the company said an unauthorized third-party copied files from Marquis’ systems containing customer information, while emphasizing the incident was limited to Marquis systems and did not compromise client institutions’ own systems.

Reporting by The Record and BleepingComputer said the exposed data included names, addresses, phone numbers, dates of birth, Social Security numbers, Taxpayer Identification Numbers and financial account information. BleepingComputer also reported Marquis previously said the attackers gained access through a SonicWall firewall, a detail that has appeared in breach notices and follow-up coverage.

Public state breach portals underscore the breadth of the incident. A Washington state filing tied to Marquis listed 269,773 Washington residents affected in a notice naming dozens of impacted institutions, while California’s breach portal shows Marquis filed a sample consumer notification identifying the breach date as Aug. 14, 2025.

The revised 672,075 total may still not capture the full downstream impact. The Record noted outside researchers and law firms have estimated the broader tally across individual institution notices could run higher, while Comparitech has separately tracked a larger cumulative total based on customer-by-customer disclosures. Still, Marquis’ updated filing gives credit unions and banks their clearest official benchmark yet for a vendor breach that has already surfaced repeatedly across the credit union system.