About 22k WAB customers impacted by a zero-day attack on a third-party vendor

Western Alliance Bank (WAB) has disclosed that a data breach at its third-party vendor’s secure file transfer software has compromised personal information for nearly 22,000 customers.

In a letter to potentially affected customers, the Arizona-based regional bank–operating over 50 branches with $80 billion in assets–disclosed that forensic analysis indicated unauthorized access to financial data, social security numbers, and other sensitive information.

“We reviewed the contents of the files acquired by the third party to determine if they contained any personal information,” the bank said in the letter. “On February 21, 2025, we determined that the files contained some of your personal information, including your name and Social Security number. The files may have also contained your date of birth, financial account number, driver’s license number, tax identification number, and/or passport, if you provided it to Western Alliance.”