Off-by-one error in Telephony in Apple iOS before 6 allows remote attackers to cause a denial of service (buffer overflow and connectivity outage) via a crafted user-data header in an SMS message.
https://exchange.xforce.ibmcloud.com/vulnerabilities/78722
http://support.apple.com/kb/HT5503
http://lists.apple.com/archives/security-announce/2012/Sep/msg00003.html