A vulnerability in the SDP negotiation logic of the Cisco Cisco Unified IP Phone 9951, Cisco Unified IP Phone 9971 and the Cisco Unified IP Phone 8961 could allow an unauthenticated, remote attacker to cause the phone to reboot. The vulnerability is due to improper processing of crafted SDP packets. An attacker could exploit this vulnerability by sending crafted SDP packets to the phone to cause the phone to reload. Cisco has confirmed the vulnerability in a security notice; however, software updates are not available. To exploit this vulnerability, an attacker must be able to send crafted SDP packets to the targeted device, which may reside on trusted, internal networks that the attacker may need access to. This access requirement decreases the likelihood of a successful exploit. Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.