VulnerabilityPublished 12 Jan 2024Updated 3 Jun 2025

CVE-2024-21597: Juniper Networks Junos OS · Resource Exposure

Affects Juniper Networks Junos OSSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 12:29 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Juniper Networks Junos OS	Affected 0 – 22.3 6 affected builds	Fixed in–

AI-suggested

European organizations should prioritize upgrading Junos OS on MX Series routers to the fixed versions: 20.4R3-S9 or later, 21.2R3-S3 or later, 21.4R3-S5 or later, 22.1R3 or later, 22.2R3 or later, and 22.3R2 or later. Where immediate patching is not feasible, network administrators should review and tighten firewall policies, especially those applied on the lo0 interface and routing-instance configurations, to detect and block anomalous traffic patterns that could exploit this bypass. Implementing strict ingress and egress filtering on interfaces connected to untrusted networks can reduce exposure. Monitoring routing-instance traffic for inconsistencies or unexpected routing updates can help identify exploitation attempts. Employing network segmentation to isolate critical routing infrastructure and limiting management access to trusted networks further reduces risk. Additionally, organizations should enable detailed logging and alerting on MX Series devices to capture suspicious traffic that may indicate attempts to exploit this vulnerability. Coordination with Juniper Networks support for guidance and applying recommended security best practices for Abstracted Fabric deployments is advised.

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.

Impact

For European organizations, especially those operating large-scale networks or service provider infrastructures using Juniper MX Series routers, this vulnerability poses a risk of unauthorized access to network control functions. The bypass of lo0 firewall filters could allow attackers to inject or manipulate routing or control plane traffic, potentially leading to routing disruptions, traffic interception, or lateral movement within the network. While the vulnerability does not directly impact confidentiality or availability, the integrity compromise can facilitate further attacks or network misconfigurations. Critical infrastructure operators, telecom providers, and large enterprises relying on Juniper MX platforms for core routing or data center interconnects in Europe could be affected. The risk is heightened in environments employing Abstracted Fabric architectures with routing-instances configured, which are common in advanced network segmentation and virtualization scenarios. Given the unauthenticated, network-based nature of the exploit, attackers could attempt to leverage this vulnerability remotely without prior access, increasing the threat surface. However, the absence of known exploits in the wild and the medium severity rating suggest that immediate widespread exploitation is not yet observed, but proactive mitigation is essential to prevent future attacks.

CWE-668Exposure of Resource to Wrong Sphere (opens in a new tab)
Class weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Authorization (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Jul 2025, 14:40 UTC

WeaknessesCWE-668

Technical details

References

Community reviews

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