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Junos CVE-2026-21913

HIGH
Improper Initialization (CWE-665)
2026-01-15 sirt@juniper.net
7.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
CVE Published
Jan 15, 2026 - 21:16 nvd
HIGH 7.5

DescriptionCVE.org

An Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on EX4000 models allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).

On EX4000 models with 48 ports (EX4000-48T, EX4000-48P, EX4000-48MP) a high volume of traffic destined to the device will cause an FXPC crash and restart, which leads to a complete service outage until the device has automatically restarted.

The following reboot reason can be seen in the output of 'show chassis routing-engine' and as a log message:

reason=0x4000002 reason_string=0x4000002:watchdog + panic with core dump

This issue affects Junos OS on EX4000-48T, EX4000-48P and EX4000-48MP:

  • 24.4 versions before 24.4R2,
  • 25.2 versions before 25.2R1-S2, 25.2R2.

This issue does not affect versions before 24.4R1 as the first Junos OS version for the EX4000 models was 24.4R1.

AnalysisAI

Unauthenticated network-based attackers can cause a denial of service on Juniper EX4000-48T, EX4000-48P, and EX4000-48MP switches by sending high-volume traffic that crashes the FXPC component and forces a device restart. The vulnerability stems from improper resource initialization in the Internal Device Manager and results in complete service outage until automatic recovery completes. Affected versions include Junos OS 24.4 before 24.4R2 and 25.2 before 25.2R1, with no patch currently available.

Technical ContextAI

Affects Junos. An Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on EX4000 models allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).

On EX4000 models with 48 ports (EX4000-48T, EX4000-48P, EX4000-48MP) a high volume of traffic destined to the device will cause an FXPC crash and restart, which leads to a complete service outage until the device has automatically restarted.

The following reboot reason ca

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

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CVE-2026-21913 vulnerability details – vuln.today

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