CVE-2025-54003 is a critical Remote File Inclusion vulnerability found in Mikado-Themes Depot, a PHP-based application used for content or theme management. The vulnerability stems from improper validation and control of filenames passed to PHP's include or require statements, which are used to incorporate external files into the application at runtime. Because the application fails to properly sanitize or restrict these inputs, an attacker can supply a crafted filename that points to a remote malicious file hosted on an attacker-controlled server. When the application includes this remote file, it executes the attacker's code with the privileges of the web server user, leading to remote code execution (RCE). This vulnerability affects all versions of Depot up to and including 1.16. The CVSS 3.1 base score of 9.8 reflects the vulnerability's network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits have been reported yet, the vulnerability is highly exploitable and can lead to full system compromise, data theft, defacement, or service disruption. The issue was reserved in July 2025 and published in January 2026, but no official patches or mitigations have been linked yet, increasing the urgency for organizations to implement defensive controls.

For European organizations, the impact of this vulnerability is substantial. Successful exploitation can lead to complete system compromise, allowing attackers to execute arbitrary commands, steal sensitive data, manipulate or delete content, and disrupt services. This is particularly critical for organizations relying on Mikado-Themes Depot for web content management, e-commerce, or customer-facing portals, as it can result in data breaches, reputational damage, regulatory fines under GDPR, and operational downtime. Given the criticality and ease of exploitation, attackers could automate attacks at scale, targeting multiple organizations simultaneously. The lack of authentication requirements means any external attacker can attempt exploitation remotely, increasing the attack surface. Additionally, the vulnerability could be leveraged as a foothold for lateral movement within corporate networks, escalating the threat beyond the web server. The absence of known exploits in the wild currently provides a window for proactive defense, but the risk remains high due to the vulnerability's nature and severity.

1. Immediate mitigation should focus on restricting the include/require statements to only allow local, trusted files by implementing strict input validation and sanitization on all filename parameters. 2. Employ PHP configuration directives such as 'allow_url_include=Off' to prevent inclusion of remote files. 3. Use web application firewalls (WAFs) to detect and block suspicious requests attempting to exploit file inclusion, especially those containing URL schemes or unexpected file paths. 4. Monitor web server logs for unusual patterns or attempts to access include parameters with external URLs or directory traversal sequences. 5. Isolate the web server environment using containerization or sandboxing to limit the impact of potential exploitation. 6. Regularly update and patch Mikado-Themes Depot once official fixes become available. 7. Conduct code reviews and security assessments of custom themes or plugins that might also use include/require statements. 8. Educate development teams on secure coding practices to prevent similar vulnerabilities in future releases. 9. Consider implementing runtime application self-protection (RASP) solutions to detect and block exploitation attempts in real time.