CVE-2026-21902

Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root

State: Published
Severity: 9.3 Critical
Published: Feb 25, 2026
Updated: Mar 4, 2026
Reserved: Jan 5, 2026

Description

An Incorrect Permission Assignment for Critical Resource vulnerability in the On-Box Anomaly detection framework of Juniper Networks Junos OS Evolved on PTX Series allows an unauthenticated, network-based attacker to execute code as root.

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. 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.

This issue affects Junos OS Evolved on PTX Series:

* 25.4 versions before 25.4R1-S1-EVO, 25.4R2-EVO.

This issue does not affect Junos OS Evolved versions before 25.4R1-EVO.

This issue does not affect Junos OS.

Scores

CVSS	Score	Vector	Source
4.0	9.3 Critical	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/AU:Y/R:U/RE:M/U:Red	juniper
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	juniper

Weaknesses

CWE-732 Incorrect Permission Assignment for Critical Resource

Affected Products

Product	Versions
Junos OS EvolvedJuniper Networks	25.4 to before 25.4R1-S1-EVO, 25.4R2-EVOAffected before 25.4R1-EVONot affected

References

https://supportportal.juniper.net/JSA107128vendor-advisory
https://kb.juniper.net/JSA107128vendor-advisory
https://github.com/watchtowrlabs/watchTowr-vs-JunosEvolved-CVE-2026-21902/blob/main/watchTowr-vs-JunosEvolved-CVE-2026-21902.pyexploit

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