An Improper Handling of Length Parameter Inconsistency vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a network based, unauthenticated attacker to cause an RPD crash leading to a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. Upon receipt of a malformed BGP flowspec update, RPD will crash resulting in a Denial of Service. This issue affects Juniper Networks Junos OS: All versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2; 20.3 versions prior to 20.3R1-S1, 20.3R2; Juniper Networks Junos OS Evolved: All versions prior to 20.1R3-EVO; 20.2 versions prior to 20.2R2-EVO; 20.3 versions prior to 20.3R2-EVO;