A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. A remote attacker, who can create valid DNS replies, could use this flaw to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in get_rdata() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
https://www.tenable.com/cyber-exposure/2021-threat-landscape-retrospective
https://www.tenable.com/blog/dnspooq-seven-vulnerabilities-identified-in-dnsmasq
https://www.jsof-tech.com/disclosures/dnspooq/
https://www.debian.org/security/2021/dsa-4844
https://security.gentoo.org/glsa/202101-17
https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html