The kernel in Juniper Junos 10.4 before 10.4R14, 11.4 before 11.4R8, 11.4X27 before 11.4X27.43, 12.1 before 12.1R6, 12.1X44 before 12.1X44-D20, 12.2 before 12.2R4, and 12.3 before 12.3R2, in certain VLAN configurations with unrestricted arp-resp and proxy-arp settings, allows remote attackers to cause a denial of service (device crash) via a crafted ARP request, aka PR 842091.