Arizona-based Western Alliance Bank experienced a security breach after an attack on a third-party file transfer program which compromised personal data of 21,899 individuals. The attack, which occurred between October 12 and 24, led to unauthorized access and exfiltration of names, Social Security numbers, birthdates, driver's license numbers, tax identification numbers, passports, and financial account numbers. The Clop ransomware operation claimed responsibility, alleging the exploit was via a vulnerability in the Cleo file sharing tool. The incident's ramifications extended to other companies such as Hewlett Packard Enterprise and Thomson Reuters, prompting further investigations.

The Arizona Attorney General's Office reported a data breach involving Western Alliance Bank on January 27, 2025. The breach occurred between October 12, 2024, and October 24, 2024, when a third-party vendor's secure file transfer software was exploited, potentially exposing personal information including names and Social Security numbers. The number of affected individuals is currently unknown.