CVE-2009-4691 in Classified Linktrader Script
Summary
by MITRE
SQL injection vulnerability in addlink.php in Classified Linktrader Script allows remote attackers to execute arbitrary SQL commands via the slctCategories parameter.
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Analysis
by VulDB Data Team • 05/02/2026
The vulnerability identified as CVE-2009-4691 represents a critical sql injection flaw within the Classified Linktrader Script application. This vulnerability specifically affects the addlink.php component where user input is improperly sanitized before being incorporated into database queries. The slctCategories parameter serves as the primary attack vector, allowing malicious actors to inject arbitrary sql commands that bypass normal authentication and authorization mechanisms. The flaw stems from inadequate input validation and improper query construction practices that fail to separate sql logic from data input.
This vulnerability operates under the well-known CWE-89 category which classifies sql injection as a weakness where untrusted data is directly incorporated into sql commands without proper sanitization or parameterization. The attack surface is particularly concerning as it enables remote code execution capabilities, allowing threat actors to manipulate database contents, extract sensitive information, or potentially escalate privileges within the application environment. The vulnerability affects the fundamental data integrity and confidentiality aspects of the classified linktrader system, making it a prime target for cybercriminals seeking unauthorized access to classified advertising data.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on the classified linktrader script for business operations. Remote attackers can exploit this flaw to gain unauthorized access to user data, advertising listings, and potentially sensitive business information stored within the database. The vulnerability also aligns with several ATT&CK techniques including T1190 for exploitation of vulnerabilities and T1071.004 for application layer protocol usage. Organizations may face regulatory compliance violations, data breaches, and reputational damage if this vulnerability remains unpatched, particularly in environments handling sensitive classified information.
Mitigation strategies for CVE-2009-4691 should prioritize immediate implementation of proper input validation and parameterized queries to prevent sql injection attacks. The recommended approach involves applying the official security patch released by the software vendor, which typically includes input sanitization routines and proper query parameterization. Organizations should also implement web application firewalls to monitor and filter suspicious sql injection attempts, conduct regular security assessments, and establish robust database access controls. Additionally, implementing the principle of least privilege for database accounts and regular security audits will significantly reduce the potential impact of such vulnerabilities. The remediation process should include thorough testing to ensure that the patch does not introduce compatibility issues while maintaining the application's core functionality.