An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker to cause a Denial of Service (DoS). If a BGP update message is received over an established BGP session, and that message contains a specific, optional transitive attribute, this session will be torn down with an update message error. This issue cannot propagate beyond an affected system as the processing error occurs as soon as the update is received. This issue is exploitable remotely as the respective attribute will propagate through unaffected systems and intermediate AS (if any). Continuous receipt of a BGP update containing this attribute will create a sustained Denial of Service (DoS) condition. Since this issue only affects 22.3R1, Juniper strongly encourages customers to move to 22.3R1-S1. Juniper SIRT felt that the need to promptly warn customers about this issue affecting the 22.3R1 versions of Junos OS and Junos OS Evolved warranted an Out of Cycle JSA. This issue affects: Juniper Networks Junos OS version 22.3R1. Juniper Networks Junos OS Evolved version 22.3R1-EVO. This issue does not affect: Juniper Networks Junos OS versions prior to 22.3R1. Juniper Networks Junos OS Evolved versions prior to 22.3R1-EVO.