Apple released  a security update today:

• APPLE-SA-2009-08-12-1  Security Update 2009-004

  This update address an issue with dynamic DNS updates with the BIND DNS server. An attacker could send a specially crafted update that could cause the DNS service to terminate.

  The security content of this update is:

  • BIND: CVE-2009-0696

More information should be available here soon on Apple's Security Update web site.