CVE-2026-101954: Junos OS and Junos OS Evolved: Unauthenticated network access causes full device takeover when J-Web is enabled

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-14 · updated 2026-10-16
Weakness: CWE-287

Description

An Improper Authentication vulnerability in the J-Web management interface and its NETCONF session handling of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to obtain root-level device configuration access and take over the device via a reachable J-Web HTTP or HTTPS service when web management is enabled.

Affected products

Juniper Junos OS: from 25.2 before 25.2R2-S2; from 25.4 before 25.4R1-S3; from 26.2 before 26.2R1-S2 — fixed in 25.2R2-S2, 25.4R1-S3, 26.2R1-S2
Juniper Networks Junos OS Evolved: from 25.2 before 25.2R2-S2-EVO; from 25.4 before 25.4R1-S3-EVO; from 26.2 before 26.2R1-S2-EVO; from 25.2X100 before 25.2X100-D35-EVO; from 25.4X300 before 25.4X300-D40-EVO; 23.4X100 — fixed in 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO

How to fix

Upgrade to a fixed version: Juniper Junos OS 25.2R2-S2, 25.4R1-S3, 26.2R1-S2; Juniper Networks Junos OS Evolved 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4X300-D40-EVO. Check the vendor advisory for mitigations.

References

https://supportportal.juniper.net/JSA112187

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