A Buffer Overflow vulnerability in the PFE of Juniper Networks Junos OS on SRX series allows an unauthenticated network based attacker to cause a Denial of Service (DoS). The PFE will crash when specific traffic is scanned by Enhanced Web Filtering safe-search feature of UTM (Unified Threat management). Continued receipt of this specific traffic will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS: 20.2 versions prior to 20.2R3-S4 on SRX Series; 20.3 versions prior to 20.3R3-S3 on SRX Series; 20.4 versions prior to 20.4R3-S3 on SRX Series; 21.1 versions prior to 21.1R3-S1 on SRX Series; 21.2 versions prior to 21.2R2-S2, 21.2R3 on SRX Series; 21.3 versions prior to 21.3R2 on SRX Series; 21.4 versions prior to 21.4R2 on SRX Series. This issue does not affect Juniper Networks Junos OS versions prior to 20.2R1.