An Incorrect Behavior Order vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on EX4300 Series allows an unauthenticated, network-based attacker to cause an integrity impact to networks downstream of the vulnerable device.
When an output firewall filter is applied to an interface it doesn't recognize matching packets but permits any traffic.
This issue affects Junos OS 21.4 releases from 21.4R1 earlier than 21.4R3-S6.
This issue does not affect Junos OS releases earlier than 21.4R1.
CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).
No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table