flowd in Juniper Junos 10.4 before 10.4S14, 11.2 and 11.4 before 11.4R6-S2, and 12.1 before 12.1R6 on SRX devices, when certain Application Layer Gateways (ALGs) are enabled, allows remote attackers to cause a denial of service (daemon crash) via crafted TCP packets, aka PRs 727980, 806269, and 835593.