On QFX and PTX Series, receipt of a malformed packet for J-Flow sampling might crash the FPC (Flexible PIC Concentrator) process which causes all interfaces to go down. By continuously sending the offending packet, an attacker can repeatedly crash the FPC process causing a sustained Denial of Service (DoS). This issue affects both IPv4 and IPv6 packet processing. Affected releases are Juniper Networks Junos OS on QFX and PTX Series: 17.4 versions prior to 17.4R2-S1, 17.4R3; 18.1 versions prior to 18.1R3-S1; 18.2 versions prior to 18.2R1-S3, 18.2R2; 17.2X75 versions prior to 17.2X75-D91, 17.2X75-D100.