Juniper Junos OS up to 23.4R2-S6/24.2R2-S3 on EX4100 IRB Interface initialization of resource

Summaryinfo

A vulnerability categorized as problematic has been discovered in Juniper Junos OS up to 23.4R2-S6/24.2R2-S3 on EX4100. Affected by this issue is some unknown functionality of the component IRB Interface. The manipulation results in initialization of resource. This vulnerability is reported as CVE-2026-33773. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Juniper Junos OS up to 23.4R2-S6/24.2R2-S3 on EX4100. Affected is an unknown functionality of the component IRB Interface. The manipulation with an unknown input leads to a initialization of resource vulnerability. CWE is classifying the issue as 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. This is going to have an impact on integrity. CVE summarizes:

An Incorrect Initialization of Resource vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX Series and QFX Series device allows an unauthenticated, network-based attacker to cause an integrity impact to downstream networks. When the same family inet or inet6 filter is applied on an IRB interface and on a physical interface as egress filter on EX4100, EX4400, EX4650 and QFX5120 devices, only one of the two filters will be applied, which can lead to traffic being sent out one of these interfaces which should have been blocked. This issue affects Junos OS on EX Series and QFX Series: * 23.4 version 23.4R2-S6, * 24.2 version 24.2R2-S3. No other Junos OS versions are affected.

The advisory is available at kb.juniper.net. This vulnerability is traded as CVE-2026-33773 since 03/23/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. 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 04/10/2026).

Upgrading to version 23.4R2-S7 or 24.2R2-S4 eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS

Version

• 23.4R2-S6
• 24.2R2-S3

License

• commercial

Website

• Vendor: https://www.juniper.net/

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