Citigroup confirmed publicly that its Citi Mobile iPhone application has a major security flaw. The Citi Mobile application is used by Citibank customers to manage their bank accounts from their iPhone or iPod Touch. The application reportedly stored sensitive information — including account numbers, payment information, and security access codes — in a hidden file on the user’s phone. This file may also have been transferred to a PC if a user synced his or her phone with their machine. Before panic overtakes you, there is no indication that these files have been compromised by any known exploit. Nonetheless, Citibank is telling its customers to upgrade to the latest version of its application which deletes these hidden files. The updated version was released on July 19th and is available for download from the App store.