Cyber Resilience

CVE-2024-21603

Juniper Junos 20.4 … 22.3

Published
12 January 2024
Modified
17 June 2026
Patch / advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0051 40th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2024-21603 is a medium-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Juniper Junos. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 40th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

An Improper Check for Unusual or Exceptional Conditions vulnerability in the kernel of Juniper Network Junos OS on MX Series allows a network based attacker with low privileges to cause a denial of service. If a scaled configuration for Source…

more

class usage (SCU) / destination class usage (DCU) (more than 10 route classes) is present and the SCU/DCU statistics are gathered by executing specific SNMP requests or CLI commands, a 'vmcore' for the RE kernel will be seen which leads to a device restart. Continued exploitation of this issue will lead to a sustained DoS. This issue only affects MX Series devices with MPC10, MPC11 or LC9600, and MX304. No other MX Series devices are affected. This issue affects Juniper Networks Junos OS: * All versions earlier than 20.4R3-S9; * 21.2 versions earlier than 21.2R3-S6; * 21.3 versions earlier than 21.3R3-S5; * 21.4 versions earlier than 21.4R3; * 22.1 versions earlier than 22.1R3; * 22.2 versions earlier than 22.2R2; * 22.3 versions earlier than 22.3R2.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
T1529 System Shutdown/Reboot Impact
Adversaries may shutdown/reboot systems to interrupt access to, or aid in the destruction of, those systems.
Why these techniques?

The vulnerability allows a low-privileged network-based attacker to trigger a kernel crash and device restart (vmcore) via specific SNMP requests or CLI commands on affected Junos OS MX Series devices, enabling endpoint denial of service through application/system exploitation and system shutdown/reboot for sustained DoS.

CVEs Like This One

CVE-2023-28979Same product: Juniper Junos
CVE-2024-39530Same product: Juniper Junos
CVE-2024-30397Same product: Juniper Junos
CVE-2025-60004Same product: Juniper Junos
CVE-2025-60011Same product: Juniper Junos
CVE-2023-28975Same product: Juniper Junos
CVE-2024-21601Same product: Juniper Junos
CVE-2026-0203Same product: Juniper Junos
CVE-2024-21614Same product: Juniper Junos
CVE-2026-21903Same product: Juniper Junos

Affected Assets

juniper
junos
20.4, 21.2, 21.3, 21.4, 22.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 7 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-754

Requires detection and response to audit logging failures as an unusual or exceptional condition.

addresses: CWE-754

Implements detection of unusual or exceptional conditions followed by safe mode entry, reducing the window for exploitation of unchecked conditions.

addresses: CWE-754

Training ensures users perform required checks for unusual or exceptional conditions as part of contingency roles, limiting attacker leverage from skipped validations.

addresses: CWE-754

IR testing directly validates checks for unusual or exceptional conditions that could indicate security incidents.

addresses: CWE-754

Requires ongoing monitoring of organization-defined metrics and analysis, enabling checks for unusual or exceptional conditions.

addresses: CWE-754

Security testing routinely checks for unusual or exceptional inputs/conditions, identifying missing validation steps that flaw remediation then resolves.

addresses: CWE-754

Requires detection of unusual conditions followed by a controlled transition to the defined failure state.

addresses: CWE-754

MTTF determination forces explicit checks for conditions that precede predictable component failure.

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 development practices directly require proper checks and handling for exceptional conditions throughout the SDLC.

DE.CM-09 partial match
prevents

Runtime monitoring of software and environments can detect adverse events triggered by unhandled exceptional conditions.

PR.PS-04 partial match
prevents

Generating logs of exceptions and errors enables detection of improper handling of unusual conditions.

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.

detects

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

A.8.15 Logging partial match
detects

Logging can record unhandled exceptions but does not prevent the weakness itself.

detects

Monitoring may detect symptoms of unhandled conditions but does not eliminate the root weakness.

prevents

Secure development life cycle mandates exception handling and input validation that directly prevent missing checks for unusual conditions.

prevents

Application security requirements explicitly call for handling of exceptional conditions and error paths.

prevents

Secure system architecture and engineering principles require robust error and exception handling mechanisms.

Hardening callouts derived

Configuration rules from DISA STIG baselines that reduce the attack surface for weaknesses of the type cited by this CVE. Derived transitively via CVE→CWE→STIG over `controls_xwalks` (authoritative rows only).

Oracle Linux 8 (2 rules)
  • V-248573 The OL 8 file integrity tool must notify the system administrator (SA) when changes to the baseline configuration or anomalies in the operation of any security functions are discovered within an organizationally defined frequency. via CWE-754
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-754
Oracle Linux 9 (1 rule)
  • V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. via CWE-754

References