The snmp_trap_decode function in the SNMP NAT helper for Linux kernel before 2.6.16.18 allows remote attackers to cause a denial of service (crash) via unspecified remote attack vectors that cause failures in snmp_trap_decode that trigger (1) frees of random memory or (2) frees of previously-freed memory (double-free) by snmp_trap_decode as well as its calling function, as demonstrated via certain test cases of the PROTOS SNMP test suite.