# CVE-2026-21902: Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root

> Unauthenticated remote attackers can execute code as root on Juniper PTX routers due to improper permission assignment in the anomaly detection framework.

- **Severity:** Critical 9.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Feb 2026
- **Updated:** 4 Mar 2026
- **Also known as:** GHSA-5w57-gjvc-whwc

## What is CVE-2026-21902?

CVE-2026-21902 is a critical missing authorization vulnerability in Juniper Junos Os Evolved, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2026-21902?

It affects 1 product.


Products: Juniper Junos Os Evolved.

## How do I fix CVE-2026-21902?

No fix has been published for CVE-2026-21902 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-21902 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21902 exists.

Public exploit code:

- https://github.com/watchtowrlabs/watchTowr-vs-JunosEvolved-CVE-2026-21902 (github_poc): https://github.com/watchtowrlabs/watchTowr-vs-JunosEvolved-CVE-2026-21902

## Other vulnerabilities in Juniper Junos Os Evolved

- [CVE-2023-28983](https://insights.sbomify.com/CVE-2023-28983/): Junos OS Evolved: Shell Injection vulnerability in the gNOI server (high 8.8)
- [CVE-2025-21599](https://insights.sbomify.com/CVE-2025-21599/): Denial of service in Junos OS Evolved (high 8.7)
- [CVE-2024-47502](https://insights.sbomify.com/CVE-2024-47502/): Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS (high 8.7)
- [CVE-2024-39531](https://insights.sbomify.com/CVE-2024-39531/): Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols (high 8.7)
- [CVE-2024-39562](https://insights.sbomify.com/CVE-2024-39562/): Junos OS Evolved: A high rate of SSH connections causes a Denial of Service (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21902 and fix it if it is affected.

What it is: CVE-2026-21902 is a critical missing authorization vulnerability in Juniper Junos Os Evolved, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21902 exists.

Affected product: Juniper Junos Os Evolved. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-21902/ (Markdown: https://insights.sbomify.com/CVE-2026-21902/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21902
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21902
- OSV: https://osv.dev/vulnerability/CVE-2026-21902

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21902/
Summaries are generated and may contain mistakes; the official description above is the record.