CVE 6.5 MEDIUM

Junos OS: Receipt of a specifically malformed ICMP packet causes an FPC restart_CVE-2026-0203

6.5 / 10
MEDIUM
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Description

An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS allows an unauthenticated, network-adjacent attacker sending a specifically malformed ICMP packet to cause an FPC to crash and restart, resulting in a Denial of Service (DoS).



When an ICMP packet is received with a specifically malformed IP header value, the FPC receiving the packet crashes and restarts. Due to the specific type of malformed packet, adjacent upstream routers would not forward the packet, limiting the attack surface to adjacent networks.

This issue only affects ICMPv4. ICMPv6 is not vulnerable to this issue.

This issue affects Junos OS: 



* all versions before 21.2R3-S9, 
* from 21.4 before 21.4R3-S10, 
* from 22.2 before 22.2R3-S7, 
* from 22.3 before 22.3R3-S4, 
* from 22.4 before 22.4R3-S5, 
* from 23.2 before 23.2R2-S3, 
* from 23.4 before 23.4R2-S3, 
* from 24.2 before 24.2R1-S2, 24.2R2.

Basic Information

ID CVE-2026-0203
Source juniper
Published Jan 15, 2026 at 20:17
Modified Jan 15, 2026 at 20:18

Affected Product

Vendor Juniper Networks
Product Junos OS
Affected Versions Juniper Networks Junos OS 0
Juniper Networks Junos OS 21.4
Juniper Networks Junos OS 22.2
Juniper Networks Junos OS 22.3
Juniper Networks Junos OS 22.4
Juniper Networks Junos OS 23.2
Juniper Networks Junos OS 23.4
Juniper Networks Junos OS 24.2

CWE Classification

References

💭 Join the Security Discussion

🔒 Your email address will not be published. Required fields are marked *

⚠️ Please be respectful and constructive in your comments. Security discussions should remain professional.