Cash App says data breach could affect millions of users

More than 8 million users of mobile payments service Cash App could be affected in a data breach involving a former employee who took records containing customer names and account numbers.

While account user names and passwords were not affected, the mobile payments app is now notifying customers of the breach, it disclosed in an April 4 filing with the Securities and Exchange Commission. Cash App is owned by Block, formerly known as Square, a financial payments company headed by Twitter co-founder Jack Dorsey,.

Block said in the filing that it "recently determined that a former employee downloaded certain reports" belonging to Cash App. That information included users' full names and brokerage account numbers, a unique identifier for a person's stock activity on Cash App Investing. For some customers, the compromised data also included "brokerage portfolio value, brokerage portfolio holdings and/or stock trading activity for one trading day," according to Block.