2010 — Equifax: An unknown number of current and former employees…

An unknown number of current and former employees of credit reporting firm Equifax received W-2 forms in the mail with their Social Security numbers visible through a window on the envelope. Some of the tax forms mailed by Equifax's payroll vendor through the U.S. Postal Service had the Social Security number in a Control Number field, which was partially or fully viewable through the return address window.