Juniper Junos OS before 12.1X44-D55, 12.1X46 before 12.1X46-D40, 12.1X47 before 12.1X47-D25, 12.3 before 12.3R10, 12.3X48 before 12.3X48-D20, 13.2 before 13.2R8, 13.2X51 before 13.2X51-D40, 13.3 before 13.3R7, 14.1 before 14.1R5, 14.1X53 before 14.1X53-D18 or 14.1X53-D30, 14.1X55 before 14.1X55-D25, 14.2 before 14.2R4, 15.1 before 15.1R2, and 15.1X49 before 15.1X49-D10 allow remote attackers to cause a denial of service via a malformed IGMPv3 packet, aka a "multicast denial of service."