Canonical example of OS command injection. CGI program does not neutralize "|" metacharacter when invoking a phonebook program.
CVE-2001-1246
Language interpreter's mail function accepts another argument that is concatenated to a string used in a dangerous popen() call. Since there is no neutralization of this argument, both OS Command Injection (CWE-78) and Argument Injection (CWE-88) are possible.
CVE-2002-0061