CVE-2021-4455 in Smart Product Review
Summary
by MITRE • 04/19/2025
The Wordpress Plugin Smart Product Review plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in all versions up to, and including, 1.0.4. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.
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Analysis
by VulDB Data Team • 04/19/2025
The vulnerability identified as CVE-2021-4455 affects the Smart Product Review plugin for WordPress, specifically versions up to and including 1.0.4. This represents a critical security flaw that stems from inadequate input validation mechanisms within the plugin's file upload functionality. The issue creates a pathway for unauthenticated attackers to bypass security controls and upload malicious files to the target WordPress installation, potentially leading to complete system compromise.
The technical root cause of this vulnerability lies in the absence of proper file type validation within the plugin's upload handling code. According to CWE-434, this weakness falls under the category of Unrestricted Upload of File with Dangerous Type, where the application allows file uploads without sufficient validation of the file contents or extensions. The plugin fails to implement proper MIME type checking, file extension filtering, or content-based validation that would normally prevent the upload of executable or potentially harmful file types such as php, aspx, or other server-side script files.
The operational impact of this vulnerability is severe and far-reaching for affected WordPress installations. Attackers can exploit this flaw to upload web shells, malicious scripts, or other payload files that can be executed on the target server. This arbitrary file upload capability directly enables remote code execution, allowing threat actors to gain unauthorized access to the compromised system, potentially leading to data theft, service disruption, or further lateral movement within the network. The vulnerability affects unauthenticated users, meaning no login credentials or privileges are required to exploit the flaw, making it particularly dangerous for publicly accessible WordPress sites.
From an attack perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1190 category for Exploit Public-Facing Application, and specifically relates to T1059 for Command and Scripting Interpreter. The attack chain typically involves uploading a malicious file through the vulnerable upload endpoint, then accessing that file through the web server to execute commands on the target system. Organizations running affected versions of this plugin face significant risk, as the vulnerability can be exploited automatically by scanners and bots, making it a prime target for automated attacks.
Mitigation strategies for this vulnerability should include immediate remediation through plugin updates to version 1.0.5 or later, which addresses the file validation issue. System administrators should also implement additional security measures such as restricting file upload directories, implementing proper file type filtering at the web server level, and conducting thorough file validation on all uploaded content. Network-based protections including web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify similar weaknesses in other plugins or components, as this vulnerability demonstrates the critical importance of proper input validation in web applications.