The remote host is missing an update to the system as announced in the referenced advisory.

Update your system with the appropriate patches or software upgrades. http://unbound.nlnetlabs.nl/downloads/CVE-2011-4528.txt http://www.vuxml.org/freebsd/7ba65bfd-2a40-11e1-b96e-00215af774f0.html

The following package is affected: unbound CVE-2011-4528 Unbound before 1.4.13p2 attempts to free unallocated memory during processing of duplicate CNAME records in a signed zone, which allows remote DNS servers to cause a denial of service (daemon crash) via a crafted response.