An Improper Check for Unusual or Exceptional Conditions vulnerability in the packetIO daemon of Juniper Networks Junos OS Evolved on PTX10003 PTX10004 and PTX10008 allows an unauthenticated network-based attacker to cause a Denial of Service (DoS). Continued receipt of these crafted packets will cause a sustained Denial of Service condition. This issue affects Juniper Networks Junos OS Evolved all versions prior to 20.4R2-S3-EVO on PTX10003 PTX10004 and PTX10008. This issue does not affect: Juniper Networks Junos OS Evolved versions 21.1R1-EVO and above; Juniper Networks Junos OS.