Sefas Data Breach Exposes Nearly 200,000 Frost Bank Customers Global software vendor Sefas disclosed a data security incident that compromised sensitive personal information of 191,848 Frost Bank customers. The breach, detected on April 16, 2026, involved unauthorized access to an SFTP server used for software support, with attackers downloading files containing customer data between December 2025 and April 2026. The exposed data included names, addresses, Social Security numbers, taxpayer IDs, account numbers, dates of birth, and loan numbers. Sefas confirmed the breach was contained to the SFTP server and ceased after April 16, with no evidence of further compromise. Frost Bank was notified on April 22, 2026, and the incident was reported to Texas state regulators. Separately, the Everest ransomware gang claimed responsibility for exfiltrating 250,000 Social Security numbers from Frost Bank, listing the bank on its dark web leak site in April 2026. The group did not disclose ransom demands or payment status, and Frost Bank has not publicly responded to the claims. Sefas has offered affected individuals one year of complimentary identity protection and credit monitoring through CyberScout. The investigation, supported by external cybersecurity experts, remains ongoing.