Juniper Networks PTX Routers Affected by Critical Vulnerability

Juniper Networks this week released an out-of-band update for its Junos OS Evolved network operating system to patch a critical vulnerability.

The vulnerability, tracked as CVE-2026-21902, affects Junos OS Evolved on PTX series high-performance routers.

The issue impacts the On-Box Anomaly detection framework and it can be exploited by an unauthenticated attacker with network access to execute arbitrary code with root privileges.

“The On-Box Anomaly detection framework should only be reachable by other internal processes over the internal routing instance, but not over an externally exposed port,” Juniper said in its advisory.

The company added, “With the ability to access and manipulate the service to execute code as root a remote attacker can take complete control of the device. Please note that this service is enabled by default as no specific configuration is required.”

The security hole has been patched with the release of versions 25.4R1-S1-EVO and 25.4R2-EVO ...