net/ipv4/netfilter/ip_conntrack_core.c in Linux kernel 2.4 and 2.6, and possibly net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c in 2.6, does not clear sockaddr_in.sin_zero before returning IPv4 socket names from the getsockopt function with SO_ORIGINAL_DST, which allows local users to obtain portions of potentially sensitive memory.