CVE-2025-53436 is a vulnerability identified in the BZOTheme Monki PHP theme, specifically involving improper control over the filename used in include or require statements within the PHP code. This vulnerability manifests as a Local File Inclusion (LFI) flaw, where an attacker can manipulate the input controlling the file path to include arbitrary local files on the server. Such an inclusion can lead to disclosure of sensitive files (e.g., configuration files, password stores), execution of malicious code if combined with other vulnerabilities, or facilitate further attacks such as remote code execution through chained exploits. The affected versions include all Monki versions up to and including 2.0.4. The vulnerability was reserved in June 2025 and published in December 2025, but no CVSS score or patches are currently available, and no known exploits have been reported in the wild. The root cause is insufficient validation or sanitization of user-supplied input used in PHP include/require statements, a common source of LFI vulnerabilities. Attackers typically exploit such flaws by crafting URLs or POST requests that manipulate parameters controlling file paths. The impact depends on the server configuration, file permissions, and presence of other vulnerabilities. Since Monki is a PHP theme, it is likely used in content management systems or custom PHP applications, making web-facing servers vulnerable. The lack of authentication requirements and the potential to access sensitive files make this vulnerability particularly dangerous.

For European organizations, this vulnerability poses a significant risk to web applications using the BZOTheme Monki theme. Successful exploitation can lead to unauthorized disclosure of sensitive data such as credentials, configuration files, or personal data, violating GDPR and other data protection regulations. It can also serve as a stepping stone for further attacks, including privilege escalation or remote code execution, potentially leading to service disruption or data breaches. Organizations in sectors with high web presence, such as e-commerce, finance, and government services, are particularly vulnerable. The impact on confidentiality and integrity is high, and availability could be affected if attackers leverage the vulnerability to disrupt services. The absence of known exploits currently provides a window for proactive mitigation, but the ease of exploitation without authentication increases urgency. Additionally, compromised systems could be used for lateral movement within networks, increasing overall organizational risk.

European organizations should immediately audit their web applications to identify usage of the BZOTheme Monki theme, especially versions up to 2.0.4. Until official patches are released, implement strict input validation and sanitization on all parameters controlling file inclusion paths to prevent manipulation. Employ web application firewalls (WAFs) with rules targeting LFI attack patterns to detect and block malicious requests. Restrict PHP include paths using open_basedir directives to limit accessible files to necessary directories only. Disable unnecessary PHP functions such as allow_url_include and ensure error reporting does not leak sensitive path information. Conduct regular security assessments and code reviews focusing on file inclusion logic. Monitor logs for suspicious access patterns indicative of LFI attempts. Once patches become available from BZOTheme or third parties, apply them promptly. Consider isolating vulnerable applications in segmented network zones to reduce lateral movement risk. Finally, educate development teams on secure coding practices related to file inclusion.