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.