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.