The system configuration control (sysctl) facility in BSD based operating systems OpenBSD 2.2 and earlier, and FreeBSD 2.2.5 and earlier, does not properly restrict source routed packets even when the (1) dosourceroute or (2) forwarding variables are set, which allows remote attackers to spoof TCP connections.
rpc.mountd on Linux, Ultrix, and possibly other operating systems, allows remote attackers to determine the existence of a file on the server by attempting to mount that file, which generates different error messages depending on whether the file exists or not.