# CVE-2026-90809: HKUDS nanobot ExecTool shell.py ExecTool._spawn argument injection

> Remote attackers can inject arguments into the nanobot ExecTool shell execution, potentially leading to arbitrary code execution.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-7hvv-vr32-8c2m

## What is CVE-2026-90809?

CVE-2026-90809 is a medium-severity command injection vulnerability in HKUDS nanobot, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was identified in HKUDS nanobot up to 0.2.1. The affected element is the function ExecTool._guard_command/ExecTool._spawn of the file nanobot/agent/tools/shell.py of the component ExecTool. Such manipulation leads to argument injection. It is possible to launch the attack remotely. The name of the patch is af582246f141311d574551b7571a517bcc3df750. It is best practice to apply a patch to resolve this issue.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2026-90809?


## How do I fix CVE-2026-90809?

No fix has been published for CVE-2026-90809 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90809 being exploited?

There is no known exploitation of CVE-2026-90809 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90809 and fix it if it is affected.

What it is: CVE-2026-90809 is a medium-severity command injection vulnerability in HKUDS nanobot, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90809 in the wild and no public exploit code.

Affected product: HKUDS nanobot. 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-2026-90809/ (Markdown: https://insights.sbomify.com/CVE-2026-90809/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90809
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90809
- OSV: https://osv.dev/vulnerability/CVE-2026-90809

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90809/
Summaries are generated and may contain mistakes; the official description above is the record.