EUVD-2026-10811

Comprehensive Technical Analysis of EUVD-2026-10811

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2026-10811 affects the GetSimple CMS, specifically the massiveAdmin plugin version 6.0.3 bundled with GetSimpleCMS-CE version 3.3.22. The vulnerability allows an authenticated administrator to overwrite the gsconfig.php configuration file with arbitrary PHP code via the gsconfig editor module. This form lacks Cross-Site Request Forgery (CSRF) protection, enabling a remote unauthenticated attacker to exploit this via CSRF against a logged-in admin, achieving Remote Code Execution (RCE) on the web server.

Severity Evaluation:

• Base Score: 9.7 (Critical)
• Base Score Version: CVSS:3.1
• Base Score Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

The high base score indicates a critical vulnerability due to the potential for remote code execution, which can lead to complete system compromise. The attack vector is network-based (AV:N), requires low complexity (AC:L), no privileges (PR:N), and user interaction (UI:R). The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H).

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

1. CSRF Attack: An attacker can craft a malicious link or form that, when clicked by an authenticated admin, sends a request to the vulnerable gsconfig editor module, overwriting the gsconfig.php file with arbitrary PHP code.
2. Phishing: Attackers can use phishing emails or social engineering to trick administrators into clicking malicious links.
3. Malicious Websites: Attackers can host malicious content on websites that administrators might visit, exploiting the vulnerability through CSRF.

Exploitation Methods:

1. Crafting Malicious Requests: Attackers can create HTTP requests that mimic legitimate admin actions but include malicious payloads.
2. Automated Scripts: Attackers can use automated scripts to send CSRF requests to the vulnerable endpoint, increasing the likelihood of successful exploitation.
3. Browser Exploits: Attackers can exploit browser vulnerabilities to execute CSRF attacks without user interaction.

3. Affected Systems and Software Versions

Affected Systems:

• GetSimpleCMS-CE versions ≤ 3.3.22
• massiveAdmin plugin version 6.0.3

Software Versions:

• GetSimpleCMS-CE v3.3.22 and earlier
• massiveAdmin plugin v6.0.3

4. Recommended Mitigation Strategies

1. Update Software: Immediately update to the latest version of GetSimpleCMS-CE and the massiveAdmin plugin that includes the security fix.
2. Implement CSRF Protection: Ensure that all forms and endpoints that modify configuration files or perform critical actions have CSRF protection.
3. User Education: Educate administrators about the risks of phishing and CSRF attacks, and encourage them to be cautious with links and forms.
4. Network Security: Implement network security measures such as firewalls, intrusion detection systems (IDS), and web application firewalls (WAF) to detect and block malicious requests.
5. Regular Audits: Conduct regular security audits and vulnerability assessments to identify and mitigate potential vulnerabilities.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to organizations using GetSimpleCMS-CE, particularly those in the European Union. The potential for remote code execution can lead to data breaches, unauthorized access, and system compromise, impacting the confidentiality, integrity, and availability of information. This underscores the importance of timely patching, robust security practices, and continuous monitoring to protect against such threats.

6. Technical Details for Security Professionals

Vulnerability Details:

• Vulnerable Component: massiveAdmin plugin v6.0.3
• Vulnerable Endpoint: gsconfig editor module
• Exploit Mechanism: Lack of CSRF protection allows unauthenticated attackers to overwrite the gsconfig.php file with arbitrary PHP code.

Detection and Response:

1. Log Analysis: Monitor server logs for unusual activity, such as repeated requests to the gsconfig editor module.
2. Intrusion Detection: Use IDS/IPS to detect and block suspicious network traffic.
3. Incident Response: Have an incident response plan in place to quickly identify, contain, and remediate any successful exploitation attempts.

References:

• GitHub Security Advisory

Conclusion: The vulnerability in GetSimpleCMS-CE and the massiveAdmin plugin is critical and requires immediate attention. Organizations should prioritize updating their systems and implementing robust security measures to mitigate the risk of exploitation. Continuous monitoring and user education are essential to maintain a strong cybersecurity posture.