Juniper Session Smart Routers Vulnerability Could Let Attackers Bypass Authentication

Juniper Networks has released security updates to address a critical security flaw impacting Session Smart Router, Session Smart Conductor, and WAN Assurance Router products that could be exploited to hijack control of susceptible devices.

Tracked as CVE-2025-21589, the vulnerability carries a CVSS v3.1 score of 9.8 and a CVS v4 score of 9.3.

“An Authentication Bypass Using an Alternate Path or Channel vulnerability in Juniper Networks Session Smart Router may allow a network-based attacker to bypass authentication and take administrative control of the device,” the company said in an advisory.

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The vulnerability impacts the following products and versions –

• Session Smart Router: From 5.6.7 before 5.6.17, from 6.0.8, from 6.1 before 6.1.12-lts, from 6.2 before 6.2.8-lts, and from 6.3 before 6.3.3-r2
• Session Smart Conductor: From 5.6.7 before 5.6.17, from 6.0.8, from 6.1 before 6.1.12-lts, from 6.2 before 6.2.8-lts, and from 6.3 before 6.3.3-r2
• WAN Assurance Managed Routers: From 5.6.7 before 5.6.17, from 6.0.8, from 6.1 before 6.1.12-lts, from 6.2 before 6.2.8-lts, and from 6.3 before 6.3.3-r2

Juniper Networks said the vulnerability was discovered during internal product security testing and research, and that it’s not aware of any malicious exploitation.

The flaw has been addressed in Session Smart Router versions SSR-5.6.17, SSR-6.1.12-lts, SSR-6.2.8-lts, SSR-6.3.3-r2, and later.

“This vulnerability has been patched automatically on devices that operate with WAN Assurance (where configuration is also managed) connected to the Mist Cloud,” the company added. “As practical, the routers should still be upgraded to a version containing the fix.”

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