Incomplete blacklist vulnerability in the Quarantine feature in CoreTypes in Apple Mac OS X 10.5 before 10.5.6 allows user-assisted remote attackers to execute arbitrary code via an executable file with the content type indicating no application association for the file, which does not trigger a "potentially unsafe" warning message.

More... (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2008-4234)