Unquoted Search Path Code Execution in Studio 5000 Logix Designer

Executive Summary

CVE-2026-9128 is a code execution vulnerability in Rockwell Automation's Studio 5000 Logix Designer. The issue stems from an unquoted search path in the External Tools configuration. When executable paths in the external tools configuration file contain spaces and are not properly quoted, the operating system may resolve them to unintended executables earlier in the search order.

An attacker could exploit this by placing a malicious executable in a location within the search path. If the application runs, it may execute the attacker's code instead of the intended executable, leading to arbitrary code execution with the same permissions as the user running the application.

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Detection Guidance

To detect the vulnerability (CVE-2026-9128) on your system, you can check for unquoted search paths in the External Tools configuration of Studio 5000 Logix Designer. The issue arises when executable paths in the external tools configuration file contain spaces and are not properly quoted, allowing unintended executables to be executed.

You can inspect the External Tools configuration file manually or use commands to verify the paths. Here are some suggested steps:

• Locate the External Tools configuration file for Studio 5000 Logix Designer. This is typically found in the installation directory or user profile settings.
• Check for unquoted paths in the configuration file. For example, look for entries like 'C:\Program Files\Tool\executable.exe' instead of '"C:\Program Files\Tool\executable.exe"'.
• Use a command-line tool like 'findstr' on Windows to search for unquoted paths in the configuration file. Example command: findstr /R /C:"^[^"]* .*[^"]*$" "path_to_configuration_file". This will highlight lines with spaces that are not enclosed in quotes.
• Verify the search paths in the system's PATH environment variable to ensure no malicious executables are placed in directories that precede the intended executable paths.

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Impact Analysis

If you use Studio 5000 Logix Designer with External Tools configured, this vulnerability could allow an attacker to execute arbitrary code on your system. The impact includes:

• Unauthorized access to your system with the privileges of the user running the application.
• Potential theft, modification, or deletion of sensitive data.
• Disruption of operations if the malicious code interferes with industrial control processes.
• Further compromise of your network if the attacker uses the initial access to move laterally.

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Compliance Impact

This vulnerability could impact compliance with several standards and regulations, depending on the context of your operations:

• GDPR: If the affected system processes personal data of EU citizens, unauthorized access or data breaches resulting from this vulnerability could lead to non-compliance with GDPR's data protection requirements, potentially resulting in fines or legal action.
• HIPAA: For organizations handling protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI, violating HIPAA's security and privacy rules.
• NIST CSF/ISO 27001: The vulnerability represents a failure to implement proper access controls and secure configurations, which are core requirements of these frameworks. Exploitation could indicate non-compliance with risk management and system integrity controls.
• Industrial standards (e.g., IEC 62443): For industrial control systems, this vulnerability could violate requirements for secure system configuration and access control, potentially leading to non-compliance with industry-specific cybersecurity standards.

To maintain compliance, affected organizations should apply the necessary patches or mitigations promptly and document their actions as part of their risk management processes.

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Mitigation Strategies

To mitigate CVE-2026-9128, follow these immediate steps:

• Update Studio 5000 Logix Designer to the latest patched version if available. While the provided context does not specify a patch for this CVE, ensure all software is up to date with vendor-recommended security updates.
• Manually edit the External Tools configuration file to ensure all executable paths are properly quoted. For example, change 'C:\Program Files\Tool\executable.exe' to '"C:\Program Files\Tool\executable.exe"'.
• Restrict write permissions to directories in the system's PATH environment variable to prevent unauthorized users from planting malicious executables.
• Run Studio 5000 Logix Designer with the least privileges necessary to reduce the impact of potential arbitrary code execution.
• Monitor the system for unusual activity, such as unexpected executable launches or modifications to the External Tools configuration file.

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