The Keychain implementation in Apple Mac OS X 10.6.8 and earlier does not properly handle an untrusted attribute of a Certification Authority certificate, which makes it easier for man-in-the-middle attackers to spoof arbitrary SSL servers via an Extended Validation certificate, as demonstrated by https access with Safari.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.