Remote Code Execution in Mura CMS

Executive Summary

CVE-2026-12257 is a critical remote code execution (RCE) vulnerability in Mura CMS versions prior to 10.0.712. The flaw exists in the endpoint '/index.cfm/_api/json/v1/default', where the 'method' parameter in POST requests is not properly validated or sanitized.

This lack of validation allows a remote attacker to inject and execute arbitrary CFML (ColdFusion Markup Language) expressions. Additionally, the attacker could instantiate malicious Java objects, which could lead to a full compromise of the system's security.

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Detection Guidance

To detect the CVE-2026-12257 vulnerability on your network or system, you can check for the presence of the vulnerable endpoint and test for improper validation of the 'method' parameter in POST requests.

• Inspect your web server logs for requests to '/index.cfm/_api/json/v1/default' with suspicious or malformed 'method' parameters. Look for unusual POST requests targeting this endpoint.
• Use a vulnerability scanner or web application security tool (e.g., OWASP ZAP, Burp Suite, or Nessus) to scan for the vulnerable endpoint. Configure the scanner to send POST requests to '/index.cfm/_api/json/v1/default' and check for unexpected behavior or responses.
• Manually test the endpoint using a tool like curl to send a POST request with a benign 'method' parameter and observe the response. Example command:
• curl -X POST http://<target>/index.cfm/_api/json/v1/default -d 'method=test' -v
• If the system is vulnerable, it may process the 'method' parameter without proper validation, potentially leading to unexpected behavior or errors. However, avoid sending malicious payloads in production environments.
• Verify the installed version of Mura CMS. If it is prior to 10.0.712, the system is likely vulnerable. Check the version through the CMS admin interface or by inspecting the application files.

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Impact Analysis

If you are using an affected version of Mura CMS (prior to 10.0.712), this vulnerability could have severe consequences for your system and data.

• An attacker could gain unauthorized access to your system by exploiting the RCE flaw.
• The attacker could execute arbitrary code on your server, potentially leading to data theft, modification, or deletion.
• The vulnerability could allow the attacker to take full control of the affected system, including installing malware or backdoors for persistent access.
• Sensitive information stored on the system, such as user credentials or confidential data, could be exposed or manipulated.
• The compromise of the system could lead to service disruptions or downtime, affecting business operations.

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Compliance Impact

This vulnerability could significantly impact compliance with various standards and regulations, depending on the nature of the data and systems involved.

• GDPR (General Data Protection Regulation): If the affected system processes or stores personal data of EU citizens, a breach resulting from this vulnerability could lead to unauthorized access or disclosure of personal data. This would violate GDPR requirements for data protection and could result in hefty fines (up to 4% of global annual revenue or €20 million, whichever is higher).
• HIPAA (Health Insurance Portability and Accountability Act): If the system handles protected health information (PHI) in the U.S., exploitation of this vulnerability could lead to unauthorized access or disclosure of PHI. This would constitute a breach under HIPAA, requiring notification and potentially resulting in fines and corrective actions.
• Other standards like PCI DSS (Payment Card Industry Data Security Standard): If the system processes payment card data, a breach could violate PCI DSS requirements, leading to penalties, increased transaction fees, or loss of ability to process payments.

In general, failure to address this vulnerability could be seen as a lack of due diligence in maintaining security controls, which is a common requirement across many compliance frameworks. Organizations may face legal, financial, and reputational consequences if this vulnerability is exploited.

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Mitigation Strategies

Since no patch or official solution has been reported yet for CVE-2026-12257, the following immediate steps can help mitigate the risk:

• Restrict access to the vulnerable endpoint '/index.cfm/_api/json/v1/default' by implementing network-level controls such as firewalls or web application firewalls (WAFs). Block or monitor POST requests to this endpoint.
• Apply IP-based restrictions to limit access to the CMS admin interface and API endpoints to trusted IP addresses only.
• Disable or remove the vulnerable endpoint if it is not essential for your operations. Consult Mura CMS documentation or support for guidance on safely disabling specific API endpoints.
• Monitor network traffic and logs for suspicious activity targeting the '/index.cfm/_api/json/v1/default' endpoint. Set up alerts for unusual POST requests or attempts to exploit the 'method' parameter.
• Consider temporarily taking the affected Mura CMS instance offline or placing it behind a VPN if the risk is deemed too high and no other mitigations are feasible.
• Stay informed about updates from Mura Software or INCIBE regarding a patch or official fix for this vulnerability. Apply the patch as soon as it becomes available.

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