Cyber Resilience

CVE-2024-39537

Juniper Junos Os Evolved ≤ 21.4

Published
11 July 2024
Modified
22 January 2026
Patch / advisory
View advisory
CVSS Score v4 6.9
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0033 26th percentile
Risk Priority 40 floored blend · peak EPSS

Summary

CVE-2024-39537 is a medium-severity Improper Restriction of Communication Channel to Intended Endpoints (CWE-923) vulnerability in Juniper Junos Os Evolved. Its CVSS base score is 6.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to IA-3 (Device Identification and Authentication) and SC-23 (Session Authenticity) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An Improper Restriction of Communication Channel to Intended Endpoints vulnerability in Juniper Networks Junos OS Evolved on ACX 7000 Series allows an unauthenticated, network-based attacker to cause a limited information disclosure and availability impact to the device. Due to a…

more

wrong initialization, specific processes which should only be able to communicate internally within the device can be reached over the network via open ports. This issue affects Junos OS Evolved on ACX 7000 Series: * All versions before 21.4R3-S7-EVO, * 22.2-EVO versions before 22.2R3-S4-EVO, * 22.3-EVO versions before 22.3R3-S3-EVO, * 22.4-EVO versions before 22.4R3-S2-EVO, * 23.2-EVO versions before 23.2R2-EVO, * 23.4-EVO versions before 23.4R1-S1-EVO, 23.4R2-EVO.

CWE(s)
CWE-923

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1090.004 Domain Fronting Command And Control
Adversaries may take advantage of routing schemes in Content Delivery Networks (CDNs) and other services which host multiple domains to obfuscate the intended destination of HTTPS traffic or traffic tunneled through HTTPS.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1557.002 ARP Cache Poisoning Credential Access
Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices.
attack.mitre.org →
T1557.003 DHCP Spoofing Credential Access
Adversaries may redirect network traffic to adversary-owned systems by spoofing Dynamic Host Configuration Protocol (DHCP) traffic and acting as a malicious DHCP server on the victim network.
attack.mitre.org →
T1557.004 Evil Twin Credential Access
Adversaries may host seemingly genuine Wi-Fi access points to deceive users into connecting to malicious networks as a way of supporting follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-47490Same product: Juniper Acx7020
CVE-2026-33803Same product: Juniper Junos Os Evolved
CVE-2026-57028Same product: Juniper Junos Os Evolved
CVE-2023-44195Same product: Juniper Junos Os Evolved
CVE-2023-28971Same vendor: Juniper
CVE-2024-39531Same product: Juniper Acx7020
CVE-2024-39538Same product: Juniper Acx7020
CVE-2024-39535Same product: Juniper Acx7020
CVE-2024-47489Same product: Juniper Acx7020
CVE-2024-30406Same product: Juniper Acx7020

Affected Assets

juniper
junos os evolved
21.4, 22.2, 22.3, 22.4, 23.2 · ≤ 21.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V8.4.1
  • V10.5.5
  • V12.3.5

Mitigating Controls (NIST 800-53 r5) AI

IA-3 Device Identification and Authentication good match

Requires unique identification and authentication of devices before establishing a communications session.

SC-23 Session Authenticity good match

Enforces authenticity of communication sessions so the system only exchanges data with verified intended endpoints.

SC-8 Transmission Confidentiality and Integrity partial match

Protects transmitted information with cryptographic integrity mechanisms that implicitly verify endpoint identity.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.IR-01 full match
prevents

Network segmentation and access controls directly enforce communication only with intended endpoints.

PR.AA-03 mostly match
prevents

Authenticating services/hardware directly prevents communication with unintended endpoints.

PR.DS-02 mostly match
prevents

Data-in-transit protections commonly include certificate-based endpoint authentication to ensure correct peers.

ID.AM-03 partial match
prevents

Documenting authorized flows helps define intended endpoints but does not enforce channel restrictions at runtime.

PR.AA-04 partial match
prevents

Protecting identity assertions supports endpoint verification but is narrower than channel restriction.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication mostly match
prevents

Secure authentication mechanisms ensure the product communicates only with intended, authenticated endpoints.

A.8.20 Networks security partial match
mitigates

Network security controls directly enforce endpoint validation and channel restrictions.

A.8.21 Security of network services partial match
prevents

Security of network services includes authentication of endpoints and service-to-service channel protection.

A.8.22 Segregation of networks partial match
mitigates

Network segregation reduces exposure but does not itself validate specific endpoints.

A.8.24 Use of cryptography partial match
prevents

Cryptography can protect channels but does not guarantee correct endpoint identity without additional controls.

A.8.26 Application security requirements partial match
prevents

Application security requirements may specify endpoint validation but do not implement it.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-923
  • V-248823 OL 8 must not have the telnet-server package installed. prevents CWE-923
RHEL 7 (1 rule)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-923
RHEL 8 (2 rules)
  • V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-923
  • V-230487 RHEL 8 must not have the telnet-server package installed. prevents CWE-923

References