Integer overflow in the load_threadstack function in the Mach-O loader (mach_loader.c) in the xnu kernel in Apple Mac OS X 10.4 through 10.5.1 allows local users to cause a denial of service (infinite loop) via a crafted Mach-O binary.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2007-6261)