Keychain in Apple Mac OS X 10.3.9 and 10.4.6 might allow an application to bypass a locked Keychain by first obtaining a reference to the Keychain when it is unlocked, then reusing that reference after the Keychain has been locked.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26413
http://www.vupen.com/english/advisories/2006/1779
http://www.us-cert.gov/cas/techalerts/TA06-132A.html
http://www.securityfocus.com/bid/17951
http://securitytracker.com/id?1016072
http://secunia.com/advisories/20077
http://lists.apple.com/archives/security-announce/2006/May/msg00003.html