The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-10:02.ntpd.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-10:02.ntpd.asc

The ntpd(8) daemon is an implementation of the Network Time Protocol (NTP) used to synchronize the time of a computer system to a reference time source. If ntpd receives a mode 7 (MODE_PRIVATE) request or error response from a source address not listed in either a 'restrict ... noquery' or a 'restrict ... ignore' section it will log the even and send a mode 7 error response.