An Improper Neutralization of Equivalent Special Elements vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on PTX Series allows a unauthenticated, adjacent attacker to cause a Denial of Service (DoS).

When MPLS packets are meant to be sent to a flexible tunnel interface (FTI) and if the FTI tunnel is down, these will hit the reject NH, due to which the packets get sent to the CPU and cause a host path wedge condition. This will cause the FPC to hang and requires a manual restart to recover.

Please note that this issue specifically affects PTX1000, PTX3000, PTX5000 with FPC3, PTX10002-60C, and PTX10008/16 with LC110x. Other PTX Series devices and Line Cards (LC) are not affected.
 

The following log message can be seen when the issue occurs:

This issue affects Juniper Networks Junos OS:

• All versions earlier than 20.4R3-S8;
• 21.1 versions earlier than 21.1R3-S4;
• 21.2 versions earlier than 21.2R3-S6;
• 21.3 versions earlier than 21.3R3-S3;
• 21.4 versions earlier than 21.4R3-S5;
• 22.1 versions earlier than 22.1R2-S2, 22.1R3;
• 22.2 versions earlier than 22.2R2-S1, 22.2R3.

To be exposed to this issue FTI need to be configured:

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

This issue was seen during production usage.

This issue has been assigned CVE-2024-21600.

The following software releases have been updated to resolve this specific issue: 20.4R3-S8, 21.1R3-S4, 21.2R3-S6, 21.3R3-S3, 21.4R3-S5, 22.1R2-S2, 22.1R3, 22.2R2-S1, 22.2R3, 22.3R1, and all subsequent releases.

This issue is being tracked as PR 1653316 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).

The issue can be prevented by configuring a limit for reject packets via:

2024-01-10: Initial Publication

• 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
• CVE-2024-21600 at cve.mitre.org