Receipt of a specific MPLS packet may cause MPC7/8/9, PTX-FPC3 (FPC-P1, FPC-P2) line cards or PTX1K to crash and restart. By continuously sending specific MPLS packets, an attacker can repeatedly crash the line cards or PTX1K causing a sustained Denial of Service. Affected releases are Juniper Networks Junos OS with MPC7/8/9 or PTX-FPC3 (FPC-P1, FPC-P2) installed and PTX1K: 15.1F versions prior to 15.1F6-S10; 15.1 versions prior to 15.1R4-S9, 15.1R6-S6, 15.1R7; 16.1 versions prior to 16.1R3-S8, 16.1R4-S9, 16.1R5-S4, 16.1R6-S3, 16.1R7; 16.1X65 versions prior to 16.1X65-D46; 16.2 versions prior to 16.2R1-S6, 16.2R2-S5, 16.2R3; 17.1 versions prior to 17.1R1-S7, 17.1R2-S7, 17.1R3; 17.2 versions prior to 17.2R1-S4, 17.2R2-S4, 17.2R3; 17.2X75 versions prior to 17.2X75-D70, 17.2X75-D90; 17.3 versions prior to 17.3R1-S4, 17.3R2, 17.4 versions prior to 17.4R1-S2, 17.4R2. Refer to KB25385 for more information about PFE line cards.