The Juniper SRX Series devices with Junos 11.4 before 11.4R12-S4, 12.1X44 before 12.1X44-D40, 12.1X45 before 12.1X45-D30, 12.1X46 before 12.1X46-D25, and 12.1X47 before 12.1X47-D10, when an Application Layer Gateway (ALG) is enabled, allows remote attackers to cause a denial of service (flowd crash) via a crafted packet.