CVE-2026-3368 in Injection Guard Plugin
Summary
by MITRE • 03/21/2026
The Injection Guard plugin for WordPress is vulnerable to Stored Cross-Site Scripting via malicious query parameter names in all versions up to and including 1.2.9. This is due to insufficient input sanitization in the sanitize_ig_data() function which only sanitizes array values but not array keys, combined with missing output escaping in the ig_settings.php template where stored parameter keys are echoed directly into HTML. When a request is made to the site, the plugin captures the query string via $_SERVER['QUERY_STRING'], applies esc_url_raw() (which preserves URL-encoded special characters like %22, %3E, %3C), then passes it to parse_str() which URL-decodes the string, resulting in decoded HTML/JavaScript in the array keys. These keys are stored via update_option('ig_requests_log') and later rendered without esc_html() or esc_attr() on the admin log page. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in the admin log page that execute whenever an administrator views the Injection Guard log interface.
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Analysis
by VulDB Data Team • 03/27/2026
The vulnerability identified as CVE-2026-3368 affects the Injection Guard plugin for WordPress, representing a critical stored cross-site scripting flaw that has been present in all versions up to and including 1.2.9. This security weakness stems from inadequate input sanitization mechanisms within the plugin's core functionality, specifically within the sanitize_ig_data() function that fails to properly sanitize array keys while successfully sanitizing array values. The flaw creates a dangerous condition where malicious actors can exploit the plugin's handling of query parameters to inject persistent malicious scripts that execute in the context of administrator sessions.
The technical implementation of this vulnerability involves multiple layers of insufficient security controls that compound the risk. When a request is processed through the plugin, the system captures the query string using $_SERVER['QUERY_STRING'] and applies esc_url_raw() function which, while designed to sanitize URLs, inadvertently preserves URL-encoded special characters such as %22 (double quotes), %3E (greater than), and %3C (less than) that represent potential HTML injection points. The subsequent processing through parse_str() function then URL-decodes these strings, converting the encoded characters back into their original HTML/JavaScript form. This decoded content, now containing potentially malicious script code, becomes embedded in array keys which are then stored via update_option('ig_requests_log') function, creating a persistent storage mechanism for the malicious content.
The operational impact of this vulnerability extends beyond simple script injection, creating a serious threat to administrative security within WordPress installations. When administrators access the Injection Guard log interface through the ig_settings.php template, the stored parameter keys are echoed directly into HTML without proper output escaping mechanisms such as esc_html() or esc_attr() functions. This direct output rendering creates an ideal environment for XSS execution, as the malicious code embedded within the array keys becomes active JavaScript that runs in the administrator's browser context. The vulnerability is particularly dangerous because it requires no authentication to exploit, making it possible for unauthenticated attackers to compromise administrative sessions and potentially gain full control over WordPress installations.
This vulnerability aligns with CWE-79 (Cross-site Scripting) and follows patterns commonly associated with ATT&CK technique T1059.001 (Command and Scripting Interpreter: PowerShell) and T1059.007 (Command and Scripting Interpreter: JavaScript), demonstrating how poorly sanitized input can create persistent attack vectors within web applications. The flaw also reflects broader security principles regarding input validation and output escaping that are fundamental to preventing injection attacks across web platforms. Organizations using the Injection Guard plugin version 1.2.9 or earlier face significant risk of unauthorized access and potential data compromise, as the stored XSS vulnerability can be leveraged for session hijacking, privilege escalation, or further exploitation of the WordPress environment.
Mitigation strategies for this vulnerability must address both the immediate security gap and the underlying architectural issues within the plugin. The most effective immediate solution involves updating to a patched version of the Injection Guard plugin where the sanitize_ig_data() function properly sanitizes both array keys and values, and where the ig_settings.php template implements proper output escaping for all user-provided content. Additionally, administrators should implement web application firewalls that can detect and block suspicious query parameter patterns, and consider implementing Content Security Policy headers that limit script execution capabilities. Regular security audits of WordPress plugins should include verification of input sanitization and output escaping mechanisms, with particular attention to how query parameters and user data are handled in plugin administrative interfaces. Organizations should also establish monitoring procedures to detect unusual activity in plugin log files that might indicate exploitation attempts, and maintain up-to-date backups to facilitate rapid recovery in case of successful compromise.