Description

A vulnerability was determined in HKUDS nanobot up to 0.2.1. Impacted is the function ExecTool._guard_command/ExecTool._spawn of the file nanobot/agent/tools/shell.py of the component ExecTool. This manipulation causes incomplete blacklist. It is possible to initiate the attack remotely. Patch name: af582246f141311d574551b7571a517bcc3df750. Applying a patch is the recommended action to fix this issue.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.3",
  "pubDate": "2026-09-14T19:18:10.700Z",
  "pubdate": "2026-09-14T19:18:10.700Z",
  "executiveSummary": "The HKUDS nanobot library, specifically in versions up to 0.2.1, contains a critical security vulnerability related to input validation within the ExecTool component.\nThe vulnerability is characterized as an incomplete blacklist implementation, which allows for command injection or unauthorized execution of shell commands.\nThis flaw resides within the _guard_command and _spawn methods located in nanobot/agent/tools/shell.py.\nThe vulnerability enables remote attackers to circumvent existing security filters, potentially leading to arbitrary code execution on the host system.\nThe risk is categorized as high, as it permits an attacker to bypass intended operational restrictions and interact with the underlying shell environment in ways not explicitly authorized by the developer's blacklist.\nExploitation does not require prior authentication if the agent provides a remote interface, increasing the overall attack surface and potential for unauthorized system manipulation.",
  "technicalDetails": "The root cause of this vulnerability is an ineffective and incomplete blacklist mechanism implemented in the ExecTool._guard_command function, which acts as a gatekeeper for the ExecTool._spawn method. Instead of employing a secure 'allow-list' (positive security model) to validate executable inputs, the implementation relies on filtering out known malicious strings or characters.\nIn nanobot/agent/tools/shell.py, the _guard_command function evaluates input strings before they are passed to the _spawn method for execution. Because this blacklist is incomplete, it fails to account for various command shell escape sequences, subshell invocations, or alternative command separators (such as backticks, command chaining via operators like '&&' or '||', and input redirection) that the underlying shell interprets as valid instructions.\nThe attack flow proceeds as follows: An attacker sends a crafted malicious payload to the HKUDS nanobot agent. The input is processed by ExecTool, where _guard_command performs a validation check. Since the attacker's input uses syntax or commands that are not explicitly present in the application's limited blacklist, the _guard_command function returns a false-positive validation success. The input is then passed to _spawn, which executes the payload within the system shell context.\nBecause the vulnerability exists in the shell execution pipeline, a successful exploit grants the attacker the ability to run arbitrary commands with the same privileges as the nanobot process. This can lead to full system compromise, data exfiltration, or the installation of persistent malicious agents, depending on the environment in which the nanobot is deployed.\nThe flaw affects all versions of HKUDS nanobot up to 0.2.1. The lack of robust input sanitization and the reliance on blacklisting in shell-sensitive components represents a failure to implement defense-in-depth principles for command execution. Remediation requires moving away from blacklist-based filtering and implementing rigorous input validation, or preferably, utilizing language-native APIs that do not invoke a shell environment for process execution, thereby neutralizing shell injection vectors entirely."
}