# CVE-2026-18685: GL.iNet GL-MT3000 modem.so glc set_upgrade command injection

> Remote attackers can execute arbitrary commands on GL.iNet GL-MT3000 routers via the modem.so component, requiring immediate patching.

- **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:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Aug 2026
- **Updated:** 4 Aug 2026
- **Also known as:** GHSA-frjc-j2mw-rv29

## What is CVE-2026-18685?

CVE-2026-18685 is a critical command injection vulnerability in GL.iNet GL-MT3000, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A security vulnerability has been detected in GL.iNet GL-MT3000 up to 4.4.5. Impacted is the function set_upgrade of the file /cgi-bin/glc of the component modem.so. Such manipulation leads to command injection. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure and confirmed the existence of the vulnerability.

Weakness: CWE-77 (Improper Neutralization of Special Elements used in a Command), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2026-18685?


## How do I fix CVE-2026-18685?

No fix has been published for CVE-2026-18685 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18685 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-18685 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18685 and fix it if it is affected.

What it is: CVE-2026-18685 is a critical command injection vulnerability in GL.iNet GL-MT3000, published on 3 Aug 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-2026-18685 exists.

Affected product: GL.iNet GL-MT3000. 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-2026-18685/ (Markdown: https://insights.sbomify.com/CVE-2026-18685/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18685
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18685
- OSV: https://osv.dev/vulnerability/CVE-2026-18685

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18685/
Summaries are generated and may contain mistakes; the official description above is the record.