Product:
Junos OS
Summary
An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS allows an unauthenticated, network-adjacent attacker to send a specifically malformed ICMP packet that causes an FPC to crash and restart, resulting in a Denial of Service. This issue only affects ICMPv4 and is limited to adjacent networks due to upstream routers not forwarding the malformed packets.
Details
| Severity | Base Score | CVE |
|---|---|---|
| HIGH | 7.1 | CVE-2026-0203 |
Exploitation
To exploit this vulnerability, an attacker on an adjacent network can send a specially crafted ICMP packet with a malformed IP header to the affected device. Upon receipt of this packet, the FPC will crash and restart, leading to a Denial of Service condition. The attack is effective only against devices that have not been updated to the specified secure versions.
Affected Products
- All versions of Junos OS before 21.2R3-S9
- Junos OS 21.4 before 21.4R3-S10
- Junos OS 22.2 before 22.2R3-S7
- Junos OS 22.3 before 22.3R3-S4
- Junos OS 22.4 before 22.4R3-S5
- Junos OS 23.2 before 23.2R2-S3
- Junos OS 23.4 before 23.4R2-S3
- Junos OS 24.2 before 24.2R1-S2 and 24.2R2
Mitigation
To mitigate this vulnerability, users should upgrade their Junos OS to the latest secure versions as specified in the affected products list. Regularly applying security updates and patches will help protect against this and other vulnerabilities.