An Improper Input Validation vulnerability in Packet Forwarding Engine manager (FXPC) process of Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) by sending specific DHCPv6 packets to the device and crashing the FXPC service. Continued receipt and processing of this specific packet will create a sustained Denial of Service (DoS) condition. This issue affects only the following platforms in ACX Series: ACX500 ACX1000 ACX1100 ACX2100 ACX2200 ACX4000 ACX5048 ACX5096 devices. Other ACX platforms are not affected from this issue. This issue affects Juniper Networks Junos OS on ACX500 ACX1000 ACX1100 ACX2100 ACX2200 ACX4000 ACX5048 ACX5096: 18.4 version 18.4R3-S7 and later versions prior to 18.4R3-S8. This issue does not affect: Juniper Networks Junos OS 18.4 versions prior to 18.4R3-S7 on ACX500 ACX1000 ACX1100 ACX2100 ACX2200 ACX4000 ACX5048 ACX5096.