CVE-2024-21597 Junos OS: MX Series: In an AF scenario traffic can bypass configured lo0 firewall filters

Medium 5.3 Published 12 Jan 2024 Updated 3 Jun 2025

An unauthenticated attacker can bypass lo0 firewall filters on Juniper MX Series routers in Abstracted Fabric scenarios with routing instances.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2024-21597?

CVE-2024-21597 is a medium-severity vulnerability in Juniper Junos, published on 12 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-668

Which versions are affected by CVE-2024-21597?

It affects 1 product.

Products include Juniper Junos.

How do I fix CVE-2024-21597?

No fix has been published for CVE-2024-21597 yet. Limit exposure of the affected software until one is available.

Is CVE-2024-21597 being exploited?

There is no known exploitation of CVE-2024-21597 in the wild and no public exploit code.

All Juniper Junos vulnerabilities

Sources

Also known as GHSA-m474-q42g-p73p.