A Use After Free vulnerability in the Routing Protocol Daemon (rdp) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker to cause Denial of Service (DoS). When a BGP session flap happens, a Use After Free of a memory location that was assigned to another object can occur, which will lead to an rpd crash. This is a race condition that is outside of the attacker's control and cannot be deterministically exploited. Continued flapping of BGP sessions can create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS: All versions prior to 18.4R2-S9, 18.4R3-S11; 19.1 versions prior to 19.1R3-S8; 19.2 version 19.2R1 and later versions; 19.3 versions prior to 19.3R3-S5; 19.4 versions prior to 19.4R2-S6, 19.4R3-S6; 20.1 version 20.1R1 and later versions; 20.2 versions prior to 20.2R3-S3; 20.3 versions prior to 20.3R3-S2; 20.4 versions prior to 20.4R3-S1; 21.1 versions prior to 21.1R3-S3; 21.2 versions prior to 21.2R2-S1, 21.2R3. Juniper Networks Junos OS Evolved All versions prior to 20.4R3-S4-EVO; 21.1-EVO versions prior to 21.1R3-S2-EVO; 21.2-EVO versions prior to 21.2R3-EVO; 21.3-EVO versions prior to 21.3R2-EVO.