Buffer overflow in sqlexec for Informix SE-7.25 allows local users to gain root privileges via a long INFORMIXDIR environment variable.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2002-0896
http://www.securityfocus.com/bid/4891
http://www.iss.net/security_center/static/9219.php
http://archives.neohapsis.com/archives/bugtraq/2002-05/0270.html