CVE-2023-4666 is a critical vulnerability identified in the Form Maker by 10Web WordPress plugin, affecting all versions prior to 1.15.20. The core issue stems from improper validation of file signatures during the creation of files on the server from user input. Specifically, the plugin fails to validate or restrict the types of files that unauthenticated users can upload or create, leading to an unrestricted file upload vulnerability categorized under CWE-434 (Unrestricted Upload of File with Dangerous Type). This flaw allows attackers to upload arbitrary files, including malicious scripts, which can then be executed on the server, resulting in Remote Code Execution (RCE). The vulnerability is exploitable remotely without any authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact on confidentiality, integrity, and availability is severe, as attackers can execute arbitrary code, potentially taking full control of the affected WordPress site and underlying server infrastructure. Given the widespread use of WordPress and the popularity of 10Web’s Form Maker plugin for creating forms, this vulnerability poses a significant risk to websites using this plugin. No known exploits have been reported in the wild yet, but the high CVSS score of 9.8 underscores the critical nature of this vulnerability and the urgency for patching or mitigation.

For European organizations, the impact of this vulnerability can be substantial. Many businesses, government agencies, and non-profits in Europe rely on WordPress for their web presence, and plugins like Form Maker by 10Web are commonly used to add form functionality. Exploitation could lead to full site compromise, data breaches involving sensitive customer or citizen data, defacement, or use of compromised servers as a foothold for further attacks within the network. The ability to execute arbitrary code remotely without authentication means attackers can bypass perimeter defenses easily. This can disrupt business operations, damage reputation, and lead to regulatory penalties under GDPR if personal data is exposed. Additionally, compromised sites could be leveraged to distribute malware or conduct phishing campaigns targeting European users, amplifying the threat. Critical infrastructure or organizations with public-facing WordPress sites using this plugin are particularly at risk, as attackers may seek to exploit these as entry points for broader cyber-espionage or sabotage campaigns.

1. Immediate upgrade: Organizations should update the Form Maker by 10Web plugin to version 1.15.20 or later, where this vulnerability is patched. 2. Temporary disablement: If patching is not immediately possible, disable the Form Maker plugin to prevent exploitation. 3. Web Application Firewall (WAF): Deploy or update WAF rules to detect and block attempts to upload files with suspicious extensions or payloads targeting the plugin’s upload endpoints. 4. File upload restrictions: Implement server-side controls to restrict executable file types and enforce strict validation on uploaded files beyond plugin-level checks. 5. Monitoring and logging: Enable detailed logging of file upload activities and monitor for unusual file creation or execution patterns. 6. Incident response readiness: Prepare to investigate and remediate potential compromises by scanning for web shells or unauthorized files created via this vulnerability. 7. Harden WordPress environment: Limit plugin installations to trusted sources, regularly audit plugins for vulnerabilities, and apply the principle of least privilege to WordPress file and directory permissions to reduce impact if exploited.