An Origin Validation vulnerability in MAC address validation of Juniper Networks Junos OS Evolved on PTX10001, PTX10004, PTX10008, and PTX10016 devices allows a network-adjacent attacker to bypass MAC address checking, allowing MAC addresses not intended to reach the adjacent LAN to be forwarded to the downstream network. Due to this issue, the router will start forwarding traffic if a valid route is present in forwarding-table, causing a loop and congestion in the downstream layer-2 domain connected to the device.This issue affects Juniper Networks Junos OS Evolved on PTX10001, PTX10004, PTX10008, and PTX10016:All versions prior to 21.4R3-S5-EVO;22.1 versions prior to 22.1R3-S4-EVO;22.2 versions 22.2R1-EVO and later;22.3 versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO;22.4 versions prior to 22.4R2-S1-EVO, 22.4R3-EVO;23.2 versions prior to 23.2R1-S1-EVO, 23.2R2-EVO.