A vulnerability in Junos OS on SRX Series devices allows attackers to trigger a DoS attack by sending crafted valid traffic, which is caused by improper handling of exceptional conditions within the Packet Forwarding Engine (PFE) and leads to PFE crashes and restarts upon receiving the specific traffic.  An attacker can exploit this by continuously sending the malicious traffic, causing a sustained DoS condition and potentially impacting network resource availability.  An unauthenticated attacker on the network could use a vulnerability in Junos OS versions starting with 21.4R1 to affect SRX Series devices by causing a Denial-of-Service (DoS) condition.  Severity Assessment (CVSS) Score This vulnerability, which achieves a high severity rating according to both CVSS v3 (7.5) and v4 (8.7) scoring systems, allows an attacker to crash a critical process (PFE) by sending specific valid traffic to the device, which will lead to a service outage until the device is rebooted. A recently discovered vulnerability in Juniper’s Junos OS for SRX Series firewalls can cause a denial-of-service (DoS) condition, which exists in the Packet Forwarding Engine (PFE) and allows an unauthenticated attacker to crash the PFE through specifically crafted valid traffic.  All Junos OS versions on SRX devices starting from 21.4R1 (including 21.4, 22.1, 22.2, 22.3, and 22.4) are susceptible if they haven’t been patched with the following updates:

Source: GBHackers