Juniper Junos OS up to 24.4R0/24.4R1/25.2R1-S2/25.2R1 on EX4000 Internal Device Manager initialization of resource

Summaryinfo

A vulnerability classified as critical was found in Juniper Junos OS up to 24.4R0/24.4R1/25.2R1-S2/25.2R1 on EX4000. The affected element is an unknown function of the component Internal Device Manager. Executing a manipulation can lead to initialization of resource. This vulnerability is handled as CVE-2026-21913. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Juniper Junos OS up to 24.4R0/24.4R1/25.2R1-S2/25.2R1 on EX4000 and classified as critical. This vulnerability affects an unknown function of the component Internal Device Manager. The manipulation with an unknown input leads to a initialization of resource vulnerability. The CWE definition for the vulnerability is CWE-1419. The product attempts to initialize a resource but does not correctly do so, which might leave the resource in an unexpected, incorrect, or insecure state when it is accessed. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at supportportal.juniper.net. This vulnerability was named CVE-2026-21913 since 01/05/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 01/16/2026).

Upgrading to version 24.4R1, 24.4R2, 25.2R1-S2 or 25.2R2 eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS

Version

• 24.4R0
• 24.4R1
• 25.2R1
• 25.2R1-S2

License

• commercial

Website

• Vendor: https://www.juniper.net/

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