The WiFi component in Apple iOS before 5 stores WiFi credentials in an unspecified file, which makes it easier for remote attackers to obtain sensitive information via a crafted application.
https://exchange.xforce.ibmcloud.com/vulnerabilities/70562
http://support.apple.com/kb/HT4999
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00001.html