An issue has been found in PowerDNS Recursor 4.1.0 through 4.3.0 where records in the answer section of a NXDOMAIN response lacking an SOA were not properly validated in SyncRes::processAnswer, allowing an attacker to bypass DNSSEC validation.
lists.opensuse.org/opensuse-security-announce/2020-05/msg00052.html
www.openwall.com/lists/oss-security/2020/05/19/3
doc.powerdns.com/recursor/security-advisories/powerdns-advisory-2020-02.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NMP72NJGKBWR5WEBXAWX5KSLQUDFTG6S/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PS4ZN5XGENYNFKX7QIIOUCQQHXE37GJF/
www.debian.org/security/2020/dsa-4691