Unspecified vulnerability in Cisco IOS 12.2XNA, 12.2XNB, 12.2XNC, 12.2XND, 12.4T, 12.4XZ, and 12.4YA, when Zone-Based Policy Firewall SIP Inspection is enabled, allows remote attackers to cause a denial of service (device reload) via a crafted SIP transit packet, aka Bug ID CSCsr18691.