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 does not affect AFT-based line cards such as the MPC10, MPC11, LC4800, LC9600, and MX304.

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.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

The following software releases have been updated to resolve this specific issue: Junos OS 20.2R3-S10, 21.2R3-S9, 21.4R3-S10, 22.2R3-S7, 22.3R3-S4, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, 24.2R1-S2, 24.2R2, 24.4R1, and all subsequent releases.

This issue is being tracked as 1824879 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

There are no known workarounds for this issue.

2026-01-14: Initial Publication
2026-03-10: Clarified that AFT line cards are unaffected by this issue

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team