An Improper Handling of Exceptional Conditions vulnerability in Junos OS packet processing allows an unauthenticated, network‑adjacent attacker to send a specifically malformed ICMPv4 packet that causes the forwarding plane controller (FPC) to crash and restart. The crash results in a short‑term denial of service for the device, disrupting routing or switching functionality. The vulnerability is limited to ICMPv4 – ICMPv6 is not affected – and does not impact AFT‑based line cards such as the MPC10, MPC11, LC4800, LC9600, or MX304.

Affected products are Juniper Networks Junos OS versions preceding 21.2R3‑S9, 21.4 prior to 21.4R3‑S10, 22.2 prior to 22.2R3‑S7, 22.3 prior to 22.3R3‑S4, 22.4 prior to 22.4R3‑S5, 23.2 prior to 23.2R2‑S3, 23.4 prior to 23.4R2‑S3, and 24.2 prior to 24.2R1‑S2 or 24.2R2. All subsequent releases include the mitigation.

The CVSS score of 7.1 classifies this flaw as high severity, while the EPSS score of less than 1% indicates a low likelihood of exploitation at present. The vulnerability is not listed in the CISA KEV catalog, further suggesting limited use in widespread attacks. Exploitation requires the ability to send packets from an adjacent network segment, and no authentication is needed. However, because the impact is a DoS that can interrupt service for adjacent peers, any breach of network proximity is sufficient for an attacker to cause service disruption.