Preface: The Domain Name System (DNS) was standardized 30 years ago by IETF (RFC1034 and RFC1035). An additional standard, EDNS (RFC2671) was published in 1999 and updated in 2013 (RFC6891).

Synopsis: As time goes by, EDNS, gained importance with the wide deployment of DNSSEC, among others, which has become an essential part of the DNS protocol.
Since the nonconformity of the software code especially of the DNS software vendors.There are different workarounds on DNS software vendors. Meanwhile it is hard to avoid vulnerability occurs.

ISC Releases security updates for Bind:
CVE-2018-5744: A specially crafted packet can cause named to leak memory – https://kb.isc.org/docs/cve-2018-5744

CVE-2018-5745: An assertion failure can occur if a trust anchor rolls over to an unsupported key algorithm when using managed-keys – https://kb.isc.org/docs/cve-2018-5745

CVE-2019-6465: Zone transfer controls for writable DLZ zones were not effective – https://kb.isc.org/docs/cve-2019-6465