Cisco Security Advisory – A vulnerability in the Session Initiation Protocol (SIP) implementation in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device. To exploit this vulnerability, affected devices must be configured to process SIP messages. Cisco has released free software updates that address this vulnerability. There are no workarounds for devices that must run SIP; however, mitigations are available to limit exposure to this vulnerability.