Unbound before 1.10.1 has Insufficient Control of Network Message Volume, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.
https://nlnetlabs.nl/downloads/unbound/CVE-2020-12662_2020-12663.txt
http://www.openwall.com/lists/oss-security/2020/05/19/5
https://www.debian.org/security/2020/dsa-4694
https://www.synology.com/security/advisory/Synology_SA_20_12
https://usn.ubuntu.com/4374-1/
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00069.html
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00067.html
https://security.netapp.com/advisory/ntap-20200702-0006/
https://security.FreeBSD.org/advisories/FreeBSD-SA-20:19.unbound.asc
https://lists.debian.org/debian-lts-announce/2021/02/msg00017.html
Source: MITRE
Published: 2020-05-19
Updated: 2021-07-21
Type: CWE-674
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH