An Exposure of Resource to Wrong Sphere vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to bypass the intended access restrictions.

In an Abstracted Fabric (AF) scenario if routing-instances (RI) are configured, specific valid traffic destined to the device can bypass the configured lo0 firewall filters as it's received in the wrong RI context.

This issue affects Juniper Networks Junos OS on MX Series:

• All versions earlier than 20.4R3-S9;
• 21.2 versions earlier than 21.2R3-S3;
• 21.4 versions earlier than 21.4R3-S5;
• 22.1 versions earlier than 22.1R3;
• 22.2 versions earlier than 22.2R3;
• 22.3 versions earlier than 22.3R2.

To be exposed to this issue node-slicing must 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-2024-21597.

The following software releases have been updated to resolve this specific issue: 20.4R3-S9, 21.2R3-S3, 21.4R3-S5, 22.1R3, 22.2R3, 22.3R2, 22.4R1, and all subsequent releases.

This issue is being tracked as PR 1685129 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).

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-2024-21597 at cve.mitre.org