# CVE-2026-4129: Improper Access Controls in NI SystemLink

> Authenticated users with limited privileges can access restricted host operating system files and directories in NI SystemLink Server.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-f777-xf39-r6fm

## What is CVE-2026-4129?

CVE-2026-4129 is a high-severity missing authorization vulnerability in NI SystemLink, published on 10 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

There is an improper access control vulnerability in NI SystemLink that may allow an authenticated user with limited privileges to access host operating system files and directories that should be restricted. This vulnerability affects NI SystemLink and NI SystemLink Server versions prior to 2026 Q3.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-4129?


## How do I fix CVE-2026-4129?

No fix has been published for CVE-2026-4129 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4129 being exploited?

There is no known exploitation of CVE-2026-4129 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4129 and fix it if it is affected.

What it is: CVE-2026-4129 is a high-severity missing authorization vulnerability in NI SystemLink, published on 10 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-4129 in the wild and no public exploit code.

Affected product: NI SystemLink. 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-2026-4129/ (Markdown: https://insights.sbomify.com/CVE-2026-4129/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4129
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4129
- OSV: https://osv.dev/vulnerability/CVE-2026-4129

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4129/
Summaries are generated and may contain mistakes; the official description above is the record.