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High7.5Juniper Networks

High [CVE-2026-21913] Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on…

This high-severity Juniper Networks advisory covers CVE-2026-21913 affecting Junos, Junos OS, EX.

CVE-2026-21913 Published Jan 15, 2026Updated by vendor Jun 17, 2026
CVE-2026-21913
Affected products & platforms
Juniper NetworksSwitchesJunosEX / QFX SwitchesEX4000
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Summary

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.

Affected products named by the advisory: EX.

Affected versions
  • 24.4
  • 25.2

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions
  • 24.4R2
  • 25.2R1-S2
  • 24.4R1

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation

Upgrade to a fixed release: 24.4R2, 25.2R1-S2, 24.4R1. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Discussion(0)

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