An Improper Handling of Exceptional Conditions vulnerability in the routing protocol daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows a network based, unauthenticated attacker to cause the RPD process to crash leading to a Denial of Service (DoS). When a malformed BGP UPDATE packet is received over an established BGP session, RPD crashes and restarts. Continuous receipt of the malformed BGP UPDATE messages will create a sustained Denial of Service (DoS) condition for impacted devices. This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. This issue affects: Juniper Networks Junos OS: * All versions earlier than 20.4R3-S9; * 21.2 versions earlier than 21.2R3-S7; * 21.3 versions earlier than 21.3R3-S5; * 21.4 versions earlier than 21.4R3-S6; * 22.1 versions earlier than 22.1R3-S4; * 22.2 versions earlier than 22.2R3-S3; * 22.3 versions earlier than 22.3R3-S2; * 22.4 versions earlier than 22.4R3; * 23.2 versions earlier than 23.2R2. Juniper Networks Junos OS Evolved: * All versions earlier than 21.2R3-S7; * 21.3-EVO versions earlier than 21.3R3-S5; * 21.4-EVO versions earlier than 21.4R3-S8; * 22.1-EVO versions earlier than 22.1R3-S4; * 22.2-EVO versions earlier than 22.2R3-S3; * 22.3-EVO versions earlier than 22.3R3-S2; * 22.4-EVO versions earlier than 22.4R3; * 23.2-EVO versions earlier than 23.2R2.