Critical Juniper Junos OS Evolved PTX Router Vulnerability

THREAT INTELLIGENCE

Peer Review

4.8

Proven Trust

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Critical

CVE-2026-21902

Other

March 5, 2026

Executive Summary

CVE-2026-21902 is rated critical and enables remote code execution as root. An unauthenticated attacker can fully compromise vulnerable routers.

Key Details

Affected Platform

Attack Surface

Network accessible, unauthenticated

Recommended Action

Affected Environment

Junos OS Evolved running on Juniper PTX Series routers is affected.
These routers are widely used in ISP, telecom, and cloud networks.

Operational Impact

A successful attack allows complete router takeover by an adversary.
Attackers could control traffic handling and undermine network reliability.

Technical Root Cause

Incorrect permission assignment for a critical resource in Junos OS Evolved.
The anomaly detection service is accessible beyond intended internal use.

Recommended Mitigation

Identify PTX routers running vulnerable Junos OS Evolved versions.
Apply Juniper’s fixed releases (25.4R1-S1-EVO or 25.4R2-EVO) after testing.

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Full Technical Report

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References

Use vendor and official sources to confirm status and fixes for CVE-2026-21902.
Key references: Juniper security bulletin, NVD entry, and public reporting.