The SecurityAgent component in Mac OS X 10.4 through 10.4.10 allows attackers with physical access to bypass the authentication dialog of the screen saver and send keystrokes to a process, related to "handling of keyboard focus between secure text fields."
https://exchange.xforce.ibmcloud.com/vulnerabilities/38480
http://www.vupen.com/english/advisories/2007/3868
http://www.us-cert.gov/cas/techalerts/TA07-319A.html
http://www.securityfocus.com/bid/26444
http://securitytracker.com/id?1018951
http://secunia.com/advisories/27643
http://lists.apple.com/archives/security-announce/2007/Nov/msg00002.html