Tony Finch and Marco Davids reported an assertion failure in BIND, a
DNS server implementation, which causes the server process to
terminate. This denial-of-service vulnerability is related to a
defect in the processing of responses with DNAME records from
authoritative servers and primarily affects recursive resolvers.
For the stable distribution (jessie), this problem has been fixed in
version 1:9.9.5.dfsg-9+deb8u8.
We recommend that you upgrade your bind9 packages.