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Junos CVE-2026-21913

HIGH
Improper Initialization (CWE-665)
2026-01-15 sirt@juniper.net
7.5
CVSS 3.1
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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

DescriptionNVD

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. …

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RemediationAI

Within 7 days: Identify all affected systems and apply vendor patches promptly. Monitor vendor channels for patch availability.

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CVE-2026-21913 vulnerability details – vuln.today

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