An exploitable denial-of-service vulnerability exists in Systemd 245. A specially crafted DHCP FORCERENEW packet can cause a server running the DHCP client to be vulnerable to a DHCP ACK spoofing attack. An attacker can forge a pair of FORCERENEW and DCHP ACK packets to reconfigure the server.
https://talosintelligence.com/vulnerability_reports/TALOS-2020-1142
https://security.netapp.com/advisory/ntap-20210625-0005/
https://security.gentoo.org/glsa/202107-48
http://www.openwall.com/lists/oss-security/2021/09/07/3