A vulnerability in the implementation of the Short Message Service (SMS) handling functionality of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. The vulnerability is due to improper processing of SMS protocol data units (PDUs) that are encoded with a special character set. An attacker could exploit this vulnerability by sending a malicious SMS message to an affected device. A successful exploit could allow the attacker to cause the wireless WAN (WWAN) cellular interface module on an affected device to crash, resulting in a DoS condition that would require manual intervention to restore normal operating conditions.