This indicates an attack attempt against a denial of service vulnerability in ISC DHCP.
The vulnerability is caused by an error when the vulnerable software handles a malicious DHCP Request. It allows a remote attacker to cause a DoS via sending a crafted DHCP request.
ISC DHCP 4.1 before 4.1.1-P1 and 4.0 before 4.0.2-P1
Denial of Service
Update to latest version 4.0.2-P1 and 4.1.1-P1