CVE-2021-47916 in Simple CMS
Summary
by MITRE • 02/01/2026
Simple CMS 2.1 contains a remote SQL injection vulnerability that allows privileged attackers to inject unfiltered SQL commands in the users module. Attackers can exploit unvalidated input parameters in the admin.php file to compromise the database management system and web application.
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Analysis
by VulDB Data Team • 05/16/2026
Simple CMS 2.1 suffers from a critical remote SQL injection vulnerability that resides within its users module and represents a direct violation of CWE-89 which catalogs improper neutralization of special elements used in an SQL command. The flaw manifests when unvalidated input parameters are processed through the admin.php file without adequate sanitization or escaping mechanisms, creating an attack surface where malicious actors can inject arbitrary SQL commands directly into the database layer. This vulnerability specifically targets the administrative interface where privileged attackers can leverage their elevated access rights to manipulate the underlying database through carefully crafted SQL payloads. The exploitation process typically involves manipulating URL parameters or form inputs that are subsequently passed to database queries without proper validation, allowing attackers to execute unauthorized database operations such as data extraction, modification, or deletion. This weakness enables attackers to bypass authentication mechanisms, escalate privileges, and potentially gain complete control over the database server and associated web application infrastructure. The vulnerability aligns with ATT&CK technique T1190 which describes the exploitation of remote services for initial access, and T1071.004 which covers application layer protocol manipulation. The impact extends beyond simple data compromise as attackers can leverage this vulnerability to establish persistent access, perform data exfiltration, and potentially use the compromised database as a pivot point for further attacks within the network infrastructure. The absence of input validation and output escaping in the admin.php file creates a direct path for SQL injection attacks, making this vulnerability particularly dangerous for systems where administrative privileges are granted to trusted users who may be compromised. Organizations running Simple CMS 2.1 are advised to implement immediate mitigations including input validation, parameterized queries, and regular security updates to prevent exploitation. The vulnerability demonstrates a fundamental failure in secure coding practices and represents a classic example of how insufficient input validation can lead to complete system compromise. Security professionals should consider implementing web application firewalls and monitoring for suspicious database queries as additional protective measures against this type of attack vector. The vulnerability's exploitation potential makes it a high-priority target for threat actors and emphasizes the critical importance of maintaining up-to-date security patches and conducting regular vulnerability assessments to prevent unauthorized access to sensitive database systems.