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.