2026 Frost Bank - vendor breach and Everest-linked lawsuit allegations affecting ~109k customers
Data compromised
Alleged Social Security numbers, financial account information, and contact information
Technical writeup
Security Boulevard/CISO Whisperer reported that Frost Bank faced two proposed class-action lawsuits after a cyberattack attributed in the complaints to the Everest ransomware group allegedly exposed sensitive data for about 109,000 customers. Frost said it had been notified by a third-party vendor of unauthorized access to the vendor's systems that may have included Frost customer data, and said there was no evidence of unauthorized access to Frost's own network. The affected count and detailed fields were lawsuit allegations rather than confirmed bank disclosure at the time.
Root cause
Third-party vendor unauthorized access, with Everest ransomware allegations in lawsuits; direct Frost network access not evidenced by bank statement