The access permissions for a UNIX domain socket are ignored in Solaris 2.x and SunOS 4.x, and other BSD-based operating systems before 4.4, which could allow local users to connect to the socket and possibly disrupt or control the operations of the program using that socket.
Sysinstall in FreeBSD 2.2.1 and earlier, when configuring anonymous FTP, creates the ftp user without a password and with /bin/date as the shell, which could allow attackers to gain access to certain system resources.