bind9 - security update

This update fixes a denial of service vulnerability in BIND, a DNS server.

By making use of maliciously-constructed zones or a rogue server, an attacker
could exploit an oversight in the code BIND 9 used to follow delegations in
the Domain Name Service, causing BIND to issue unlimited queries in an attempt
to follow the delegation.

This can lead to resource exhaustion and denial of service (up to and
including termination of the named server process).

For Debian 6 Squeeze, these issues have been fixed in bind9 version 9.7.3.dfsg-1~squeeze13