An Improper Input Validation vulnerability in the Juniper DHCP Daemon (jdhcpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker to cause the jdhcpd process to crash resulting in a Denial of Service (DoS). When a specifically malformed DHCP packet is received from a DHCP client, the jdhcpd process crashes, which will lead to the unavailability of the DHCP service and thereby resulting in a sustained DoS. The DHCP process will restart automatically to recover the service. This issue will occur when dhcp-security is enabled.  This issue affects Junos OS:  * All versions before 21.2R3-S9,  * from 21.4 before 21.4R3-S10,  * from 22.2 before 22.2R3-S6,  * from 22.4 before 22.4R3-S6,  * from 23.2 before 23.2R2-S3,  * from 23.4 before 23.4R2-S4,  * from 24.2 before 24.2R2;  Junos OS Evolved:  * from 22.4 before 22.4R3-S6-EVO,  * from 23.2 before 23.2R2-S3-EVO,  * from 23.4 before 23.4R2-S4-EVO,  * from 24.2 before 24.2R2-EVO. .