Unspecified vulnerability in Cisco IOS 12.2XNA, 12.2XNB, 12.2XNC, 12.2XND, 12.4MD, 12.4T, 12.4XZ, and 12.4YA allows remote attackers to cause a denial of service (device reload) via a crafted NTPv4 packet, aka Bug IDs CSCsu24505 and CSCsv75948.