Juniper Junos 11.4 before 11.4R8, 12.1 before 12.1R5, 12.1X44 before 12.1X44-D20, 12.1X45 before 12.1X45-D15, 12.1X46 before 12.1X46-D10, and 12.1X47 before 12.1X47-D10 on SRX Series devices, allows remote attackers to cause a denial of service (flowd crash) via a malformed packet, related to translating IPv6 to IPv4.