CVE-2026-66593 in Security & Malware Scan Plugin
Summary
by MITRE • 08/20/2026
Unauthenticated SQL Injection in Security & Malware scan by CleanTalk <= 2.184 versions.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified as an unauthenticated SQL injection within the CleanTalk plugin, specifically affecting versions up to and including 2.184, represents a critical security flaw that compromises the integrity of the underlying database infrastructure. This issue stems from insufficient input validation and sanitization mechanisms when processing user-supplied data related to the Security & Malware scan functionality. Because the vulnerability is unauthenticated, it allows any remote attacker with network access to exploit this weakness without needing valid credentials or prior interaction with the application's login system. The root cause lies in the direct concatenation of unsanitized input into SQL query structures used by the plugin during its scanning operations, a classic manifestation of CWE-89 Improper Neutralization of Special Elements used in an SQL Command which is widely recognized as one of the most dangerous web application vulnerabilities due to its potential for complete data compromise.
From a technical perspective, the flaw likely resides in how the plugin handles parameters passed via HTTP requests such as GET or POST variables associated with scan configurations or status checks. When these inputs are processed by the backend PHP code and subsequently injected into MySQL queries without proper escaping using functions like mysqli_real_escape_string or prepared statements, an attacker can manipulate the query logic. By injecting malicious SQL payloads, typically involving UNION-based techniques to extract data from other tables within the same database schema, attackers can bypass intended access controls. This exploitation vector aligns with MITRE ATT&CK technique T1059 Command and Scripting Interpreter through SQL commands, allowing for remote code execution or data exfiltration depending on the specific capabilities of the Database Management System in use.
The operational impact of this vulnerability is severe, potentially leading to full database compromise. Attackers can extract sensitive information including user credentials, personal identifiable information stored by WordPress sites using CleanTalk, and administrative configuration details. In worst-case scenarios where the database server has elevated privileges or insecure configurations such as FILE privilege enabled in MySQL, an attacker might write files directly to the web root, achieving remote code execution on the host system. This transforms a simple data leak into a complete site takeover scenario, allowing for defacement, installation of persistent backdoors, and further lateral movement within the network environment hosting the vulnerable WordPress instance.
Mitigation strategies must prioritize immediate remediation through software updates. Administrators running CleanTalk versions 2.184 or older should upgrade to the latest patched version where this input validation issue has been resolved by implementing parameterized queries and strict type checking for all user inputs. In environments where patching is not immediately feasible, temporary mitigations include deploying a Web Application Firewall configured with rules specifically targeting SQL injection patterns in CleanTalk endpoints, restricting database access permissions to follow the principle of least privilege, and disabling unnecessary plugin features if they are not actively used. Regular security audits and monitoring for anomalous database query logs can also help detect exploitation attempts early before significant damage occurs.