# CVE-2026-90808: HKUDS nanobot incomplete blacklist in shell command execution

Source: https://junglewise.ai/threats/cve-2026-90808-hkuds-nanobot-incomplete-blacklist-in-shell-command-execution  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-14. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-90808 · Severity: medium · CVSS 6.3 · Published 2026-09-14

HKUDS nanobot is a lightweight AI agent framework with built-in shell execution capabilities. A flaw in the command allowlist filtering lets authenticated users bypass security restrictions and execute unintended shell commands, potentially allowing attackers to perform unauthorized actions on the host system where the agent is running.

Technologies: [HKUDS Nanobot](https://junglewise.ai/threats/technologies/nanobot). Vendors: [HKUDS](https://junglewise.ai/threats/vendors/hkuds).

## Quick answers

**Is CVE-2026-90808 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-90808 being exploited in the wild.

**How severe is CVE-2026-90808?** Medium severity, with a CVSS score of 6.3, published 14 September 2026.

**Which products and versions are affected?** HKUDS Nanobot up to 0.2.1.

**Is there a fix for CVE-2026-90808?** A patch was published on 2026-09-14: Patch commit af582246f141311d574551b7571a517bcc3df750 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-90808 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-90808?** Check whether you run HKUDS Nanobot at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the ExecTool._guard_command and ExecTool._spawn functions within nanobot/agent/tools/shell.py. The allowlist-based command filtering has an incomplete blacklist that can be bypassed through shell chaining techniques, allowing an attacker to execute arbitrary commands outside the restricted set. The attack is network-reachable and likely requires authentication or local access to the nanobot framework. An attacker can achieve remote code execution on the host system. A patch (commit af582246f141311d574551b7571a517bcc3df750) is available and recommended.

## Affected products

- HKUDS nanobot up to 0.2.1

## Timeline

- 2026-09-14: disclosed
- 2026-09-14: patched: Patch commit af582246f141311d574551b7571a517bcc3df750

## References

- [https://github.com/HKUDS/nanobot/](https://github.com/HKUDS/nanobot/)
- [https://github.com/HKUDS/nanobot/commit/af582246f141311d574551b7571a517bcc3df750](https://github.com/HKUDS/nanobot/commit/af582246f141311d574551b7571a517bcc3df750)

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