Cyber Resilience

CVE-2024-39526

Juniper Junos Os Evolved 19.4 – 21.2

Published
11 October 2024
Modified
23 January 2026
Patch / advisory
CVSS Score v4 7.1
Click a component to see what it means
Raw vectorCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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:U/V:X/RE:X/U:X
EPSS Score 0.0037 30th percentile
Risk Priority 36 floored blend · peak EPSS

Summary

CVE-2024-39526 is a high-severity Improper Handling of Exceptional Conditions (CWE-755) vulnerability in Juniper Junos Os Evolved. Its CVSS base score is 7.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 30th 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 SC-24 (Fail in Known State) and SI-17 (Fail-safe Procedures) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C lines cards, MX304 devices, and Juniper Networks Junos OS Evolved on PTX Series, allows an…

more

attacker sending malformed DHCP packets to cause ingress packet processing to stop, leading to a Denial of Service (DoS). Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. This issue only occurs if DHCP snooping is enabled. See configuration below. This issue can be detected using following commands. Their output will display the interface status going down: user@device>show interfaces <if--x/x/x> user@device>show log messages | match <if--x/x/x> user@device>show log messages ==> will display the "[Error] Wedge-Detect : Host Loopback Wedge Detected: PFE: no," logs. This issue affects: Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C line cards, and MX304: * All versions before 21.2R3-S7, * from 21.4 before 21.4R3-S6, * from 22.2 before 22.2R3-S3, * all versions of 22.3, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2; Junos OS Evolved on PTX Series: * from 19.3R1-EVO before 21.2R3-S8-EVO, * from 21.4-EVO before 21.4R3-S7-EVO, * from 22.1-EVO before 22.1R3-S6-EVO, * from 22.2-EVO before 22.2R3-S5-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S1-EVO, * from 23.2-EVO before 23.2R2-S2-EVO, * from 23.4-EVO before 23.4R2-EVO. Junos OS Evolved releases prior to 19.3R1-EVO are unaffected by this vulnerability

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1489 Service Stop Impact
Adversaries may stop or disable services on a system to render those services unavailable to legitimate users.
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-21587Same product: Juniper Junos
CVE-2024-21610Same product: Juniper Junos
CVE-2023-36832Same product: Juniper Junos
CVE-2025-21602Same product: Juniper Junos
CVE-2024-39552Same product: Juniper Junos
CVE-2024-21585Same product: Juniper Junos
CVE-2024-39541Same product: Juniper Junos
CVE-2024-39525Same product: Juniper Junos
CVE-2024-30380Same product: Juniper Junos
CVE-2025-30652Same product: Juniper Junos

Affected Assets

juniper
junos
21.2, 21.4, 22.2, 22.3, 22.4 · ≤ 21.2
juniper
junos os evolved
19.3, 21.2, 21.4, 22.1, 22.2 · 19.4 — 21.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

Mitigating Controls (NIST 800-53 r5) AI

Requires the system to fail to a known safe state on specified failures, limiting the impact of unhandled exceptional conditions.

Mandates explicit fail-safe procedures triggered by indicated failures, structurally preventing unhandled or mishandled exceptional conditions.

Requires generation of appropriate error messages on exceptional conditions, directly enforcing correct handling rather than silent or incorrect behavior.

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.PS-06 mostly match
prevents

Secure SDLC practices explicitly require proper exception and error handling during design and coding.

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.

finds

Security testing in development and acceptance verifies correct handling of exceptional conditions.

degrades

Documented operating procedures may specify exception handling but do not guarantee implementation.

A.8.15 Logging partial match
finds

Logging captures unhandled exceptions, aiding detection but not preventing the weakness.

finds

Monitoring can surface unhandled exceptions but does not enforce proper handling.

prevents

Secure SDLC mandates exception-handling requirements and testing that directly prevent improper handling of exceptional conditions.

prevents

Application security requirements explicitly include handling of error and exceptional conditions.

References