FUXA 1.2.8 Authentication Bypass and Remote Command Execution Vulnerability

FUXA, a web-based SCADA/HMI software, versions 1.2.8 and earlier, contains an authentication bypass vulnerability (CVE-2025-69985). This vulnerability allows unauthenticated attackers to execute arbitrary commands on the server by exploiting the /api/runscript endpoint. The exploit uses a crafted JavaScript payload leveraging child_process.execSync to execute commands, capturing the full standard output. This vulnerability was discovered and published in February 2026 by Joshua van der Poll, and a proof-of-concept exploit is publicly available. Successful exploitation leads to complete system compromise, emphasizing the critical need for patching and detection measures. The vulnerability has been patched in versions of FUXA greater than 1.2.8.

Attack Chain

1. An unauthenticated attacker sends a POST request to /api/runscript.
2. The attacker crafts a JSON payload containing a script parameter with malicious JavaScript code.
3. The JavaScript code utilizes the child_process.execSync function to execute arbitrary commands on the system.
4. The execSync function captures the standard output and standard error of the executed command.
5. The captured output is returned in the HTTP response.
6. The attacker parses the HTTP response to retrieve the output of the executed command.
7. The attacker can then use the command execution to perform further actions, such as reading sensitive files, installing malware, or creating new user accounts.
8. The attacker achieves full remote command execution, potentially leading to complete system compromise.

Impact

Successful exploitation of this vulnerability allows an unauthenticated attacker to execute arbitrary commands on the FUXA server. This can lead to complete system compromise, including data theft, service disruption, and the installation of malware. Given the nature of SCADA/HMI software, this could have significant consequences for industrial control systems and critical infrastructure. While specific victim numbers are unavailable, the potential impact is high due to the critical nature of the targeted software.

Recommendation

• Upgrade FUXA to a version greater than 1.2.8 to patch CVE-2025-69985.
• Deploy the Sigma rule “Detect FUXA API Runscript Exploitation” to your SIEM to identify exploitation attempts against the /api/runscript endpoint.
• Monitor web server logs for POST requests to /api/runscript with unusual or suspicious JavaScript code in the script parameter, as detected by the rule “Detect Suspicious Javascript in FUXA API Runscript”.
• Implement network segmentation to limit the blast radius of a potential compromise, isolating FUXA servers from other critical systems.