Buffer overflow in IBM Informix Dynamic Server (IDS) 9.40.TC5 through 9.40.xC7 and 10.00.TC1 through 10.00.xC3 allows attackers to execute arbitrary code via the SQLIDEBUG environment variable (envariable).
https://exchange.xforce.ibmcloud.com/vulnerabilities/28158
http://www.vupen.com/english/advisories/2006/3077
http://www.securityfocus.com/bid/19264
http://www.securityfocus.com/archive/1/443165/100/0/threaded
http://www.securityfocus.com/archive/1/443133/100/0/threaded
http://www.databasesecurity.com/informix/DatabaseHackersHandbook-AttackingInformix.pdf