A vulnerability in the interaction of SIP and Snort 3 for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to restart. This vulnerability is due to a lack of error-checking when SIP bidirectional flows are being inspected by Snort 3. An attacker could exploit this vulnerability by sending a stream of crafted SIP traffic through an interface on the targeted device. A successful exploit could allow the attacker to trigger a restart of the Snort 3 process, resulting in a denial of service (DoS) condition.