CVE-2022-40797 is a critical remote code execution (RCE) vulnerability affecting Roxy Fileman version 1.4.6. The vulnerability arises due to insufficient validation of uploaded files in the default configuration. Specifically, the default 'FORBIDDEN_UPLOADS' setting in the conf.json file only blocks files with extensions .php, .php4, and .php5, but does not block .phar files. A .phar (PHP Archive) file is a PHP-specific archive format that can contain executable PHP code. In certain realistic web server configurations, visiting a .phar file causes the PHP interpreter to process the file, which can lead to execution of malicious code embedded within the .phar archive. This means an attacker can upload a crafted .phar file and trigger remote code execution without authentication or user interaction. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) and has a CVSS v3.1 base score of 9.8, indicating critical severity. The attack vector is network-based (AV:N), requires no privileges (PR:N), and no user interaction (UI:N), with high impact on confidentiality, integrity, and availability. No patches or vendor mitigations are listed, and no known exploits in the wild have been reported yet. The vulnerability highlights a common misconfiguration and insufficient file type validation in web applications that handle file uploads, especially those relying on extension-based filtering without considering other executable file types like .phar. Exploitation could allow attackers to execute arbitrary PHP code on the server, leading to full system compromise, data theft, or service disruption.

For European organizations using Roxy Fileman 1.4.6 or similar vulnerable configurations, this vulnerability poses a severe risk. Successful exploitation can lead to complete server compromise, allowing attackers to steal sensitive data, deploy ransomware, pivot within networks, or disrupt services. Given the critical CVSS score and the ease of exploitation (no authentication or user interaction required), attackers could rapidly exploit exposed instances. This is particularly concerning for organizations in sectors with high regulatory requirements such as finance, healthcare, and government, where data breaches can result in significant legal and financial penalties under GDPR. Additionally, compromised web servers could be used as launchpads for further attacks against European infrastructure or to host malicious content. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity demands urgent attention to prevent potential exploitation. Organizations relying on Roxy Fileman or similar file upload components should consider the risk of indirect exposure through third-party integrations or legacy systems.

1. Immediate mitigation should include updating the 'FORBIDDEN_UPLOADS' configuration to explicitly block .phar files alongside other executable extensions. 2. Implement strict server-side validation of uploaded files beyond extension checks, such as MIME type verification and content inspection. 3. Employ allowlists for permitted file types rather than blocklists to reduce the risk of unknown executable formats. 4. Configure the web server to prevent execution of uploaded files in directories intended for file storage, for example by disabling PHP execution in upload directories via .htaccess or equivalent server configuration. 5. Monitor web server logs for suspicious upload attempts or access to .phar files. 6. If possible, upgrade to a newer, patched version of Roxy Fileman or replace it with a more secure file management solution. 7. Conduct regular security assessments and penetration tests focusing on file upload functionalities. 8. Employ web application firewalls (WAFs) with rules to detect and block malicious file uploads and access patterns related to .phar exploitation. 9. Educate developers and administrators about the risks of relying solely on extension-based filtering and the importance of defense-in-depth in file upload handling.