The CFCharacterSetInitInlineBuffer method in CoreFoundation.dll in Apple Safari 3.2.3 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) or possibly execute arbitrary code via a "high-bit character" in a URL fragment for an unspecified protocol.
http://www.securityfocus.com/bid/35481
http://www.securityfocus.com/archive/1/504479/100/0/threaded