CVE-2025-39463 is a remote file inclusion vulnerability affecting the Select-Themes Dessau PHP theme product versions prior to 1.9. The root cause is improper validation and control over the filename parameter used in PHP include or require statements, which allows an attacker to specify a remote file URL that the server will include and execute. This type of vulnerability enables attackers to execute arbitrary PHP code remotely, potentially leading to full system compromise. The vulnerability is exploitable over the network without authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact covers confidentiality, integrity, and availability, as attackers can read sensitive data, modify or delete files, and disrupt services. Although no public exploits have been reported yet, the critical CVSS score of 9.8 reflects the high risk. The vulnerability affects all versions of Dessau prior to 1.9, but the exact affected versions are not fully enumerated. The vulnerability was reserved in April 2025 and published in November 2025, indicating recent discovery. The lack of available patches at the time of reporting necessitates immediate mitigation steps by users. The vulnerability is particularly dangerous in shared hosting or public-facing web environments where PHP themes are used, as it can be exploited remotely with minimal barriers.

For European organizations, this vulnerability poses a severe risk, especially for those relying on PHP-based CMS platforms that utilize the Select-Themes Dessau theme. Successful exploitation can lead to unauthorized remote code execution, allowing attackers to steal sensitive data, implant backdoors, deface websites, or disrupt services. This can result in data breaches, loss of customer trust, regulatory penalties under GDPR, and operational downtime. Organizations in sectors such as finance, healthcare, e-commerce, and government, which often use PHP-based web applications, are particularly vulnerable. The ability to exploit this vulnerability remotely without authentication increases the attack surface significantly. Additionally, compromised web servers can be leveraged as pivot points for further attacks within corporate networks. The impact on confidentiality, integrity, and availability is critical, potentially affecting business continuity and compliance with European data protection laws.

1. Immediately upgrade the Select-Themes Dessau product to version 1.9 or later once a patch is available. 2. Until a patch is released, disable remote file inclusion in the PHP configuration by setting 'allow_url_include=Off' and 'allow_url_fopen=Off' in php.ini. 3. Implement strict input validation and sanitization on all parameters used in include or require statements to prevent injection of remote URLs. 4. Use web application firewalls (WAFs) to detect and block suspicious requests attempting to exploit file inclusion. 5. Restrict web server permissions to limit the files accessible by the PHP process, minimizing the impact of potential local file inclusion. 6. Monitor web server logs for unusual patterns, such as requests containing URL schemes or unexpected parameters. 7. Employ network segmentation to isolate web servers from critical internal systems. 8. Conduct regular security audits and penetration testing focused on file inclusion vulnerabilities. 9. Educate development teams on secure coding practices to avoid similar vulnerabilities in the future.