Safari in Mac OS X 10.3.9 and 10.4.2, when rendering Rich Text Format (RTF) files, can directly access URLs without performing the normal security checks, which allows remote attackers to execute arbitrary commands.
http://www.us-cert.gov/cas/techalerts/TA05-229A.html
http://www.kb.cert.org/vuls/id/709220
http://lists.apple.com/archives/security-announce/2005/Aug/msg00000.html
http://lists.apple.com/archives/security-announce/2005//Aug/msg00001.html