# CVE-2026-76866: Netcore NR255-V 1.5.130703 OS Command Argument Injection via Unquoted DDNS Parameters

> Attackers can inject command arguments via DDNS parameters to execute arbitrary code with root privileges on Netcore NR255-V routers.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** GHSA-48c9-xhf8-82q7

## What is CVE-2026-76866?

CVE-2026-76866 is a high-severity command injection vulnerability in Netcore NR255-V, published on 15 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Netcore NR255-V firmware version 1.5.130703 builds root-run command lines from unquoted user-supplied DDNS input in DDNSset_cgi.c and related ddns_Proc.c components, enabling os command argument injection. Attackers can exploit the unsanitized parameters to inject additional command arguments executed with root privileges.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command)

## Which versions are affected by CVE-2026-76866?


## How do I fix CVE-2026-76866?

No fix has been published for CVE-2026-76866 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76866 being exploited?

There is no known exploitation of CVE-2026-76866 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76866 and fix it if it is affected.

What it is: CVE-2026-76866 is a high-severity command injection vulnerability in Netcore NR255-V, published on 15 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-76866 in the wild and no public exploit code.

Affected product: Netcore NR255-V. 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-2026-76866/ (Markdown: https://insights.sbomify.com/CVE-2026-76866/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76866
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76866
- OSV: https://osv.dev/vulnerability/CVE-2026-76866

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76866/
Summaries are generated and may contain mistakes; the official description above is the record.