CVE-2016-20052 in Snews CMS
Summary
by MITRE • 04/04/2026
Snews CMS 1.7 contains an unrestricted file upload vulnerability that allows unauthenticated attackers to upload arbitrary files including PHP executables to the snews_files directory. Attackers can upload malicious PHP files through the multipart form-data upload endpoint and execute them by accessing the uploaded file path to achieve remote code execution.
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Analysis
by VulDB Data Team • 07/21/2026
The vulnerability identified as CVE-2016-20052 represents a critical security flaw in Snews CMS version 1.7 that stems from inadequate input validation and access control mechanisms. This unrestricted file upload vulnerability exists within the content management system's file handling functionality, specifically affecting the snews_files directory where uploaded content is stored. The flaw allows unauthenticated attackers to bypass normal security restrictions and directly upload malicious files to the server without proper authorization or verification processes.
The technical implementation of this vulnerability occurs through the multipart form-data upload endpoint which fails to properly validate file types or implement necessary security checks before accepting and storing uploaded files. When attackers submit files through this endpoint, the system does not verify whether the uploaded content conforms to expected file types or contains malicious code patterns. This lack of validation creates a direct pathway for attackers to upload PHP executable files or other malicious code that can be executed on the web server. The vulnerability specifically targets the snews_files directory, which serves as the default storage location for uploaded content, making it a prime target for exploitation.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with complete remote code execution capabilities on the affected server. Once a malicious PHP file is successfully uploaded, attackers can execute arbitrary commands on the web server with the privileges of the web application user. This allows for complete system compromise including data exfiltration, installation of backdoors, privilege escalation, and potential lateral movement within the network. The unauthenticated nature of the attack means that no valid credentials are required to exploit the vulnerability, making it particularly dangerous as it can be exploited by anyone with access to the vulnerable web application.
The vulnerability aligns with CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and represents a classic example of insecure file upload functionality. From an attack perspective, this vulnerability maps directly to several ATT&CK techniques including T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter, as attackers can execute code through the uploaded PHP files. The lack of proper file type validation and the absence of file content verification create multiple attack vectors that can be leveraged for various malicious activities. Organizations running Snews CMS 1.7 should immediately implement mitigations including restricting file upload functionality, implementing proper file type validation, and ensuring that uploaded files are stored outside the web root directory to prevent direct execution.
Mitigation strategies for this vulnerability should include immediate patching of the Snews CMS to version 1.7.1 or later where the file upload restrictions have been properly implemented. Additionally, administrators should implement proper input validation by checking file extensions against a whitelist of allowed types and verifying file content through magic number checks. The snews_files directory should be configured with appropriate access controls and should not be directly accessible through the web server. Network-level protections such as web application firewalls can provide additional layers of defense, while regular security audits should monitor for unauthorized file uploads. The vulnerability demonstrates the critical importance of implementing defense-in-depth strategies and proper access controls in web applications to prevent similar issues from occurring in other components of the system architecture.