Java on Apple Mac OS X 10.5.4 and 10.5.5 does not prevent applets from accessing file:// URLs, which allows remote attackers to execute arbitrary programs.
The Hash-based Message Authentication Code (HMAC) provider in Java on Apple Mac OS X 10.4.11, 10.5.4, and 10.5.5 uses an uninitialized variable, which allows remote attackers to execute arbitrary code via a crafted applet, related to an "error checking issue."