IBM Informix Dynamic Server (IDS) before 9.40.xC7 and 10.00 before 10.00.xC3 allows allows remote authenticated users to execute arbitrary commands via the (1) "SET DEBUG FILE" SQL command, and the (2) start_onpload and (3) dbexp functions.
https://exchange.xforce.ibmcloud.com/vulnerabilities/28124
https://exchange.xforce.ibmcloud.com/vulnerabilities/28121
http://www.vupen.com/english/advisories/2006/3077
http://www.securityfocus.com/bid/19264
http://www.securityfocus.com/archive/1/443185/100/0/threaded
http://www.securityfocus.com/archive/1/443133/100/0/threaded
http://www.databasesecurity.com/informix/DatabaseHackersHandbook-AttackingInformix.pdf
http://www-1.ibm.com/support/docview.wss?uid=swg21242921