The NAT code (1) ip_nat_proto_tcp.c and (2) ip_nat_proto_udp.c in Linux kernel 2.6 before 2.6.13 and 2.4 before 2.4.32-rc1 incorrectly declares a variable to be static, which allows remote attackers to cause a denial of service (memory corruption) by causing two packets for the same protocol to be NATed at the same time, which leads to memory corruption.