The remote Mac OS X host contains an application that is affected by a format string vulnerability.
The remote host is running a version of iPhoto older than version 7.1.2. Such versions are reportedly affected by a format string vulnerability. If an attacker can trick a user on the affected host into subscribing to a specially-crafted photocast, he may be able to leverage these issues to execute arbitrary code on the affected host subject to the user's privileges.
Upgrade to version 7.1.2 or higher.