CVE-2024-21597Network attack vector

Firewall-filter bypass via wrong routing-instance context

Published Jan 12, 2024 · Updated Jun 3, 2025

Exposure to the wrong sphere in Junos OS on MX Series allows remote attackers to bypass lo0 firewall filters with valid traffic. In an Abstracted Fabric deployment with routing instances configured, the Packet Forwarding Engine handles device-bound traffic in the wrong routing-instance context, so the intended lo0 filter is not applied. The flaw requires the affected AF configuration and permits filtered traffic to reach the device, without reported data disclosure or service interruption.

CVSS severity5.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Exposure to the wrong sphere in Junos OS on MX Series allows remote attackers to bypass lo0 firewall filters with valid traffic. In an Abstracted Fabric deployment with routing instances configured, the Packet Forwarding Engine handles device-bound traffic in the wrong routing-instance context, so the intended lo0 filter is not applied. The flaw requires the affected AF configuration and permits filtered traffic to reach the device, without reported data disclosure or service interruption.

The record

CVE
CVE-2024-21597
Published
Jan 12, 2024
Updated
Jun 3, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-668, T1562.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <20.4R3-S9
  2. Affected versionversion=21.2 <21.2R3-S3
  3. Affected versionversion=21.4 <21.4R3-S5
  4. Affected versionversion=22.1 <22.1R3
  5. Affected versionversion=22.2 <22.2R3
  6. Affected versionversion=22.3 <22.3R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S9; version=21.2 <21.2R3-S3; version=21.4 <21.4R3-S5; version=22.1 <22.1R3; version=22.2 <22.2R3; version=22.3 <22.3R2

Published CVSS scores

5.3Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-668Exposure of Resource to Wrong Sphere
T1562.004Impair Defenses: Disable or Modify System Firewall

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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