It seems that this has already been reported upstream in https://gitlab.isc.org/isc-projects/bind9/-/issues/1997 and was fixed in 9.16.6.
A CVE number was assigned as well, CVE-2020-8621 https://kb.isc.org/docs/cve-2020-8621.
Please pull the fix into Focal's BIND.
It seems that this has already been reported upstream in https:/ /gitlab. isc.org/ isc-projects/ bind9/- /issues/ 1997 and was fixed in 9.16.6.
A CVE number was assigned as well, CVE-2020-8621 https:/ /kb.isc. org/docs/ cve-2020- 8621.
Please pull the fix into Focal's BIND.