Help Viewer in Apple Mac OS X 10.4.11 and 10.5 before 10.5.7 does not verify that HTML pathnames are located in a registered help book, which allows remote attackers to execute arbitrary code via a help: URL that triggers invocation of AppleScript files.
lists.apple.com/archives/security-announce/2009/May/msg00002.html
secunia.com/advisories/35074
support.apple.com/kb/HT3549
www.securityfocus.com/bid/34926
www.securitytracker.com/id?1022216
www.us-cert.gov/cas/techalerts/TA09-133A.html
www.vupen.com/english/advisories/2009/1297
exchange.xforce.ibmcloud.com/vulnerabilities/50486