CVE-2025-59558 is a remote file inclusion (RFI) vulnerability found in the ThemeMove Billey WordPress theme versions prior to 2.1.6. The root cause is improper control over the filename parameter used in PHP include or require statements, which allows an attacker to specify a remote file to be included and executed by the server. This type of vulnerability enables remote code execution without requiring any authentication or user interaction, as the attacker can directly influence the file path used by the PHP interpreter. The vulnerability was publicly disclosed on October 22, 2025, with a CVSS v3.1 score of 8.1, indicating high severity. The attack vector is network-based, requiring no privileges and no user interaction, but with high attack complexity due to the need to craft a suitable remote file payload. Successful exploitation can lead to complete compromise of the web server, including data theft, website defacement, malware deployment, or pivoting to internal networks. Although no exploits are currently known in the wild, the vulnerability is critical due to its potential impact and the widespread use of WordPress themes like Billey. The lack of available patches at the time of disclosure necessitates immediate action by administrators to update to version 2.1.6 or later once available. Additional mitigations include hardening PHP configurations to disable remote file inclusion and implementing strict input validation to prevent malicious filename parameters.

For European organizations, the impact of CVE-2025-59558 can be severe. Many businesses and institutions rely on WordPress for their online presence, including e-commerce, media, and government websites. Exploitation could lead to unauthorized access to sensitive customer data, intellectual property theft, disruption of online services, and reputational damage. The ability to execute arbitrary code remotely without authentication means attackers can deploy web shells, ransomware, or other malware, potentially causing widespread operational disruption. Given the interconnected nature of European digital infrastructure, a compromised site could serve as a launchpad for further attacks within corporate or governmental networks. Additionally, compliance with GDPR and other data protection regulations means that breaches resulting from this vulnerability could lead to significant legal and financial penalties. The high CVSS score reflects the critical nature of the threat, emphasizing the need for rapid remediation to protect confidentiality, integrity, and availability of affected systems.

1. Immediately update the ThemeMove Billey theme to version 2.1.6 or later once the patch is available to ensure the vulnerability is fixed. 2. Until patching is possible, disable PHP's allow_url_include directive in the php.ini configuration to prevent remote file inclusion. 3. Implement strict input validation and sanitization on all parameters that influence file inclusion to ensure only safe, expected filenames are processed. 4. Employ Web Application Firewalls (WAFs) with rules designed to detect and block attempts to exploit file inclusion vulnerabilities. 5. Conduct regular security audits and code reviews of custom themes and plugins to identify similar insecure coding practices. 6. Monitor web server logs for suspicious requests that attempt to include remote files or unusual URL parameters. 7. Restrict file permissions on the web server to limit the impact of any successful exploitation. 8. Educate development and IT teams about secure coding practices related to file inclusion and PHP configuration hardening.