CVE-2017-5520 in GeniXCMS
Summary
by MITRE
The media rename feature in GeniXCMS through 0.0.8 does not consider alternative PHP file extensions when checking uploaded files for PHP content, which enables a user to rename and execute files with the `.php6`, `.php7` and `.phtml` extensions.
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Analysis
by VulDB Data Team • 05/13/2026
The vulnerability identified as CVE-2017-5520 resides within GeniXCMS version 0.0.8 and earlier, exploiting a critical flaw in the media rename functionality that directly impacts file validation processes. This weakness stems from inadequate sanitization of file extensions during the upload and rename operations, creating an avenue for arbitrary code execution through seemingly innocuous file name modifications. The flaw specifically targets the CMS's file type verification mechanism, which fails to account for alternative PHP extensions beyond the conventional .php format.
The technical implementation of this vulnerability demonstrates a classic input validation bypass scenario where the application's security controls are circumvented through extension manipulation rather than content inspection. When users attempt to rename media files through the CMS interface, the system performs insufficient checks to prevent the execution of PHP code through alternative extensions such as .php6, .php7, and .phtml. This oversight represents a failure in proper file extension filtering and a lack of comprehensive security controls that should validate all potential PHP execution contexts regardless of file extension.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full system compromise capabilities. An attacker who gains access to the CMS upload functionality can leverage this flaw to execute malicious code on the web server, potentially leading to data breaches, system infiltration, and complete server takeover. The vulnerability is particularly concerning because it allows execution of PHP code through extensions that are often overlooked in security configurations, making traditional web application firewalls and security scanners less effective at detecting malicious activity.
This vulnerability maps directly to CWE-434, which addresses the insecure upload of code, and aligns with ATT&CK technique T1190, representing the exploitation of vulnerabilities in web applications. The flaw represents a failure in the principle of least privilege and proper input validation, where the CMS does not adequately enforce security boundaries around file operations. The implications are particularly severe because the vulnerability exists within a core functionality of the CMS, making it accessible to any user with upload privileges, potentially including low-privilege accounts or even unauthenticated users if the CMS configuration permits such access.
The recommended mitigations include implementing comprehensive file extension validation that explicitly blocks all PHP-related extensions including .php6, .php7, and .phtml, alongside proper content-type checking and file signature validation. Organizations should also implement proper access controls to limit upload capabilities to trusted administrators only, and deploy web application firewalls with custom rules to detect and block attempts to rename files with potentially dangerous extensions. Additionally, regular security audits of CMS configurations and automated vulnerability scanning should be implemented to identify similar oversights in other applications and prevent exploitation of similar weaknesses across the organization's digital infrastructure.