Juniper Junos 11.4 before 11.4R8, 12.1X44 before 12.1X44-D35, 12.1X45 before 12.1X45-D25, 12.1X46 before 12.1X46-D20, 12.1X47 before 12.1X47-D10, 12.2 before 12.2R9, 12.3R2 before 12.3R2-S3, 12.3 before 12.3R3, 13.1 before 13.1R4, and 13.2 before 13.2R1 allows remote attackers to cause a denial of service (assertion failure and rpd restart) via a crafted BGP FlowSpec prefix.