Incomplete Command Blacklist in GoClaw 3.11.3

Executive Summary

CVE-2026-15625 is a vulnerability in nextlevelbuilder GoClaw version 3.11.3 and earlier. It affects the function ExecApprovalManager.CheckCommand in the file internal/tools/exec_approval.go.

The vulnerability involves an incomplete blacklist mechanism in the execution approval system. Specifically, when the system is configured with tools.execApproval.security=allowlist, it checks only the outer command token (e.g., 'env') against the allowlist, but the execution layer passes the full command string to the shell (sh -c). This inconsistency allows an attacker to embed malicious shell payloads inside an allowed wrapper command.

For example, an attacker could use a command like 'env /bin/sh -c 'echo VULNERABLE_BYPASS > marker.txt'' to bypass the allowlist check. The policy layer extracts only the base binary name (env) for allowlist matching, while the execution layer runs the full command, enabling unauthorized command execution.

This flaw arises due to inconsistent command parsing between the policy and execution layers, leading to potential unauthorized actions such as file writes, arbitrary shell execution, or further compromise of the host system.

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Detection Guidance

To detect this vulnerability on your network or system, you can check if the affected version of GoClaw (3.11.3 or earlier) is running and if the `tools.execApproval.security=allowlist` configuration is enabled. The vulnerability allows bypassing the allowlist by using a transparent wrapper command, so you can test for it by attempting to invoke commands that should be blocked.

• Check the GoClaw version: Verify the installed version of GoClaw to confirm if it is 3.11.3 or earlier. This can typically be done by reviewing the application logs, configuration files, or running a version check command if supported by the software.
• Inspect the configuration: Look for the `tools.execApproval.security=allowlist` setting in the GoClaw configuration files to confirm if the allowlist feature is enabled.
• Test for the vulnerability: Use a command like `env /bin/sh -c 'echo VULNERABLE_BYPASS > marker.txt'` via the `POST /v1/tools/invoke` endpoint. If the command executes successfully and creates the `marker.txt` file, the system is vulnerable. Ensure you have proper authorization before performing such tests.
• Monitor network traffic: Use network monitoring tools to inspect traffic to the `POST /v1/tools/invoke` endpoint. Look for unusual or unexpected command invocations that may indicate an attempt to exploit this vulnerability.

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Impact Analysis

If you are using GoClaw version 3.11.3 or earlier, this vulnerability could have several impacts:

• Unauthorized command execution: An authenticated operator with low privileges could execute arbitrary commands on the host system, bypassing the intended security controls.
• Data compromise: Attackers could read, modify, or delete sensitive data stored on the system, leading to data breaches or loss.
• System compromise: The vulnerability could allow attackers to gain further access to the system, escalate privileges, or move laterally within a network.
• Operational disruption: Malicious commands could disrupt services, corrupt files, or cause downtime for critical applications.

The vulnerability is rated as High severity with a CVSS score of 8.8, indicating a significant risk of impact on confidentiality, integrity, and availability of the affected system.

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Compliance Impact

This vulnerability could impact compliance with several common standards and regulations in the following ways:

• GDPR (General Data Protection Regulation): If the vulnerability leads to unauthorized access or exposure of personal data, it could result in a data breach. GDPR requires organizations to implement appropriate security measures to protect personal data. Failure to address this vulnerability could lead to non-compliance, fines, or legal action.
• HIPAA (Health Insurance Portability and Accountability Act): For organizations handling protected health information (PHI), this vulnerability could allow unauthorized access to sensitive patient data. HIPAA mandates strict security controls to safeguard PHI, and exploitation of this flaw could result in violations and penalties.
• ISO 27001: This standard requires organizations to manage information security risks systematically. The vulnerability represents a failure in access control and secure configuration, which could lead to non-conformity with ISO 27001 requirements.
• PCI DSS (Payment Card Industry Data Security Standard): If the affected system processes payment card data, this vulnerability could lead to unauthorized access or data theft. PCI DSS requires strict access controls and secure configurations, and this flaw could result in non-compliance.

Organizations using GoClaw should assess their exposure to this vulnerability and apply the available patch to maintain compliance with these and other relevant regulations.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps to reduce the risk of exploitation.

• Upgrade GoClaw: Apply the patch by upgrading to a version of GoClaw later than 3.11.3. This is the most effective way to resolve the vulnerability.
• Disable the allowlist feature temporarily: If upgrading is not immediately possible, consider disabling the `tools.execApproval.security=allowlist` configuration until the patch can be applied. This may limit functionality but reduces the risk of exploitation.
• Restrict access to the `/v1/tools/invoke` endpoint: Limit access to the endpoint to trusted users or systems only. Use network-level controls such as firewalls or API gateways to restrict access.
• Monitor for suspicious activity: Increase monitoring of the `POST /v1/tools/invoke` endpoint for unusual command invocations. Log and review all commands executed through this endpoint to detect potential exploitation attempts.
• Review and update the allowlist: If the allowlist feature must remain enabled, review the list of allowed commands to ensure no wrapper commands (e.g., `env`, `sh`, `bash`) are included. Remove any commands that could be used to bypass the allowlist.

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