/usr/ucb/ps in Sun Microsystems Solaris 8 and 9, and certain earlier releases, allows local users to view the environment variables and values of arbitrary processes via the -e option.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1470
https://exchange.xforce.ibmcloud.com/vulnerabilities/25460
http://www.vupen.com/english/advisories/2006/1123
http://www.securityfocus.com/bid/19662