The iPhone SMS app contains a bug that could allow someone to send a text message that appears to come from any number that the sender specifies. The researcher who discovered the bug said that it could be used by attackers to spoof messages from a bank or credit card company and send the victim to a target site controlled by the attacker. The advent of mobile banking apps, some of which use SMS messages for out-of-band authentication, makes this kind of attack vector perhaps more worrisome and useful for attackers.
Source: https://threatpost.com/researcher-finds-iphone-bug-allows-sms-spoofing-081712/76925/