Approximately 20,000 current and former employees' names, addresses and Social Security numbers may have been exposed.
Bloomberg reports approximately 20,000 U.S. Internal Revenue Service (IRS) employees' personal information may have been exposed when an employee took the data home on an unencrypted USB drive, then plugged that USB drive into an Internet-connected and unsecured home computer (h/t ESET).
It is beyond me how some people can do that, it is just so basic. Systems need to be put into place to prevent it happening.
Microsoft® Windows Insider MVP - Windows Security