Detection Guidance

This vulnerability occurs during concurrent login operations within an active CODESYS Visualization session, where authentication data is insufficiently isolated and credentials may be exposed between users.

To detect this vulnerability on your system, monitor for concurrent login attempts in active visualization sessions, especially focusing on the use of the "User Management -> Login" input action.

Since the issue can be triggered via both local and remote access, network monitoring tools could be used to observe multiple simultaneous login requests to the CODESYS Visualization service.

Specific commands are not provided in the available resources, but general approaches include:

• Using network packet capture tools (e.g., tcpdump or Wireshark) to identify concurrent login attempts to the affected service.
• Checking application logs on the HMI or PLC for overlapping login events or unusual authentication activity.
• Reviewing visualization session logs for evidence of multiple users logging in simultaneously.

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Executive Summary

CVE-2026-0393 is a vulnerability in the CODESYS Visualization login dialog where authentication data is not sufficiently isolated during concurrent login operations.

This flaw allows an authenticated visualization user to obtain credentials entered by another user, potentially with higher privileges.

The issue only affects login operations within an active visualization session and can be triggered via both local and remote access.

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Impact Analysis

This vulnerability can allow a low privileged user to access credentials of other users, including those with higher privileges.

As a result, an attacker could escalate their privileges within the system, potentially gaining unauthorized access to sensitive functions or data.

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Mitigation Strategies

To mitigate the vulnerability in CODESYS Visualization login dialog, users can avoid using the "User Management -> Login" input action and instead use "User Management -> Logout" followed by a new login.

Alternatively, if property handling in visualization settings is not required, it can be disabled to reduce risk.

The recommended remediation is to update CODESYS Visualization to version 4.10.0.0, which involves recompiling affected projects and downloading the updated application to the HMI or PLC.

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Compliance Impact

The vulnerability allows an authenticated visualization user to obtain credentials entered by another user, potentially with higher privileges, due to insufficient isolation of authentication data during concurrent login operations.

This exposure of credentials could lead to unauthorized access to sensitive information, which may impact compliance with data protection standards and regulations such as GDPR and HIPAA that require strict controls on access to personal and sensitive data.

Mitigating the vulnerability by updating to the fixed version or applying recommended workarounds is important to maintain compliance with these standards.

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