Those customers that conduct their mobile banking by means of their iPhones have to make an upgrade. According to Citigroup, a security flaw is found in the older app that secreted information about account on smartphones.
It should be admitted that it would be trivial in case someone accesses the hidden file. But banking information can be saved with the help of the Citi Mobile app. So it means that bill payments, account numbers as well as access codes will be saved in a hidden file on your iPhone.
As a matter of fact, the same information can be saved on Windows OS as well as Mac but in this case it is necessary to sync your iPhone by means of iTunes.

Because of the identified bug, Citi had upgraded the software on the App Store and warned its customers about changes.

The update is responsible to correct the problem, i.e. it removes any Citi Mobile information that can be saved to users’ computers as well as iPhones.

The last update was made on July 19. The version 2.0.3 offers security enhancements as well as bug fixes.

So due to the update it would be hard for hackers to access the saved data and file remotely.