Smsd in SMS Server Tools (SMStools) before 1.4.8 allows remote attackers to execute arbitrary commands via shell metacharacters (backquotes) in message text, as described with the term "string format vulnerability" by some sources.
http://www.securityfocus.com/bid/4268
http://www.iss.net/security_center/static/8433.php
http://www.isis.de/members/~s.frings/smstools/history.html
http://archives.neohapsis.com/archives/bugtraq/2002-03/0103.html