How can this vulnerability impact me? :

This vulnerability allows an authenticated attacker to inject and store malicious JavaScript code that executes in the browsers of other users who visit the affected page.

• It can lead to unauthorized actions performed on behalf of other users.
• It may result in theft of sensitive information such as session tokens or credentials.
• It can degrade user trust and potentially compromise the integrity of the affected system.

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Can you explain this vulnerability to me?

CVE-2026-34813 is a stored Cross-Site Scripting (XSS) vulnerability affecting Endian Firewall versions 3.3.25 and earlier. It occurs in the /cgi-bin/proxyuser.cgi endpoint via the "user" parameter.

An authenticated attacker can inject arbitrary JavaScript code through this parameter. This malicious code is then stored on the server and executed whenever other users view the affected page.

This vulnerability is classified under CWE-79, which involves improper neutralization of input during web page generation.

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How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability affects Endian Firewall versions 3.3.25 and earlier, specifically the /cgi-bin/proxyuser.cgi endpoint via the "user" parameter. Detection involves checking if your system is running a vulnerable version and if the endpoint is accessible.

To detect potential exploitation or presence of the vulnerability, you can monitor HTTP requests to the /cgi-bin/proxyuser.cgi endpoint for suspicious or unexpected JavaScript code in the "user" parameter.

Example commands to detect this might include using network monitoring tools or web server logs to search for requests containing script tags or JavaScript code in the "user" parameter.

• Using grep on web server logs: grep -i 'proxyuser.cgi' /var/log/httpd/access_log | grep -i 'user=.*<script'
• Using curl to test the endpoint (requires authentication): curl -u username:password 'http://target/cgi-bin/proxyuser.cgi?user=<script>alert(1)</script>' -v

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How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

CVE-2026-34813 is a stored cross-site scripting (XSS) vulnerability that allows an authenticated attacker to inject arbitrary JavaScript code executed by other users. Such vulnerabilities can potentially lead to unauthorized access to user data or session hijacking, which may impact the confidentiality and integrity of information.

While the CVE description and resources do not explicitly mention compliance with standards like GDPR or HIPAA, stored XSS vulnerabilities generally pose risks that could lead to violations of data protection requirements under these regulations, especially if personal or sensitive data is exposed or manipulated.

Therefore, organizations using affected versions of Endian Firewall should consider this vulnerability as a factor in their compliance risk assessments and apply necessary patches or mitigations to maintain compliance.

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What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include:

• Upgrade Endian Firewall to a version later than 3.3.25 where this vulnerability is fixed.
• Restrict access to the /cgi-bin/proxyuser.cgi endpoint to trusted users only.
• Implement input validation or sanitization on the "user" parameter to prevent injection of JavaScript code.
• Monitor logs for suspicious activity related to the proxyuser.cgi endpoint.

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