The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-05:04.ifconf.asc

Upgrade your system to the appropriate stable release or security branch dated after the correction date https://secure1.securityspace.com/smysecure/catid.html?in=FreeBSD-SA-05:04.ifconf.asc

The SIOCGIFCONF ioctl allows a user process to ask the kernel to produce a list of the existing network interfaces and copy it into a buffer provided by the user process. In generating the list of network interfaces, the kernel writes into a portion of a buffer without first zeroing it. As a result, the prior contents of the buffer will be disclosed to the calling process.