IBM Informix Dynamic Server (IDS) before 9.40.xC8 and 10.00 before 10.00.xC4 stores passwords in plaintext in shared memory, which allows local users to obtain passwords by reading the memory (product defects 171893, 171894, 173772).
https://exchange.xforce.ibmcloud.com/vulnerabilities/28132
http://www.vupen.com/english/advisories/2006/3077
http://www.securityfocus.com/bid/19264
http://www.securityfocus.com/archive/1/443195/100/0/threaded
http://www.securityfocus.com/archive/1/443133/100/0/threaded
http://www.databasesecurity.com/informix/DatabaseHackersHandbook-AttackingInformix.pdf