Debian Bullseye DLA-4050-1 critical: bind9 denial of service

It is possible to construct a zone such that some queries to it will generate
responses containing numerous records in the Additional section. An attacker
sending many such queries can cause either the authoritative server itself or
an independent resolver to use disproportionate resources processing the
queries. Zones will usually need to have been deliberately crafted to exploit
this flaw.

For Debian 11 bullseye, this problem has been fixed in version
1:9.16.50-1~deb11u3.

We recommend that you upgrade your bind9 packages.

For the detailed security status of bind9 please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/bind9

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS