How to report security issues to Apple?
The Apple Product Security page states:


  To report security issues that affect Apple products, please contact: product-security@apple.com
  ...
  PGP key information
  You can use Apple's Product Security PGP key to encrypt sensitive information sent via e-mail. The e-mail address is used to monitor for potential product security issues. Because we focus our response efforts to have the greatest impact across Apple's product line, we generally will not respond to the e-mail messages unless further information is needed for a security issue.