An Exposure of Resource to Wrong Sphere vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX 300 Series allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS). Specific valid link-local traffic is not blocked on ports in STP blocked state but is instead sent to the control plane of the device. This leads to excessive resource consumption and in turn severe impact on all control and management protocols of the device. This issue affects Juniper Networks Junos OS: * 21.2 version 21.2R3-S3 and later versions earlier than 21.2R3-S6; * 22.1 version 22.1R3 and later versions earlier than 22.1R3-S4; * 22.2 version 22.2R2 and later versions earlier than 22.2R3-S2; * 22.3 version 22.3R2 and later versions earlier than 22.3R3-S1; * 22.4 versions earlier than 22.4R2-S2, 22.4R3; * 23.2 versions earlier than 23.2R1-S1, 23.2R2. This issue does not affect Juniper Networks Junos OS 21.4R1 and later versions of 21.4.