CVE-2024-3635 in Post Grid Plugin
Summary
by MITRE • 09/30/2024
The Post Grid WordPress plugin before 7.5.0 does not sanitise and escape some of its Grid settings, which could allow high privilege users such as Editor and above to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/09/2025
The Post Grid WordPress plugin vulnerability CVE-2024-3635 represents a critical stored cross-site scripting flaw affecting versions prior to 7.5.0. This vulnerability specifically targets the plugin's Grid settings functionality where insufficient sanitization and escaping mechanisms leave malicious code exposed to persistent execution. The flaw operates within the WordPress content management system's permission model, exploiting the trust placed in high-privilege user roles such as Editors and Administrators. Security researchers have identified that even in environments where the unfiltered_html capability is properly restricted - a common multisite configuration practice - these elevated users can still inject malicious scripts that persist across page loads and user sessions.
The technical implementation of this vulnerability stems from the plugin's failure to properly validate and escape user input within its Grid configuration parameters. When administrators or editors modify grid settings through the WordPress admin interface, the plugin processes these inputs without adequate sanitization measures. This creates an environment where malicious payloads can be stored within the plugin's configuration data and subsequently executed whenever the affected grid elements are rendered on web pages. The vulnerability specifically affects the plugin's handling of dynamic content parameters that are meant to define grid layouts, column configurations, and display settings. According to CWE-79, this represents a classic stored cross-site scripting vulnerability where the malicious input is first stored on the server and then executed in the context of other users' browsers. The flaw demonstrates poor input validation practices and inadequate output escaping mechanisms that are fundamental requirements for preventing XSS attacks in web applications.
The operational impact of CVE-2024-3635 extends beyond simple script execution, as it provides attackers with potential access to sensitive administrative functions and data. High-privilege users with Editor-level access or higher can leverage this vulnerability to inject malicious JavaScript that could steal session cookies, redirect users to phishing sites, or perform unauthorized administrative actions. In multisite WordPress installations where the unfiltered_html capability is typically restricted, the vulnerability becomes particularly dangerous as it bypasses these security restrictions. The stored nature of the vulnerability means that the malicious code persists even after the initial injection, creating a long-term threat that can affect multiple users over extended periods. This vulnerability aligns with ATT&CK technique T1566.001 for initial access through malicious content and T1059.001 for command and control through script injection. The persistence of the attack vector makes it particularly concerning for organizations managing multiple users with varying privilege levels.
Mitigation strategies for CVE-2024-3635 should prioritize immediate plugin updates to version 7.5.0 or later, where the sanitization and escaping mechanisms have been properly implemented. System administrators should conduct thorough vulnerability assessments of their WordPress installations to identify any instances where affected plugin versions are still in use. The remediation process must include not only updating the plugin but also reviewing and cleaning any previously injected malicious content from the affected grid configurations. Organizations should implement comprehensive input validation and output escaping measures across all custom plugin development and third-party plugin usage to prevent similar vulnerabilities. Security monitoring should include regular checks for unusual administrative activities and unexpected content modifications. Additionally, implementing web application firewalls and content security policies can provide additional layers of protection against exploitation attempts. The vulnerability serves as a reminder of the importance of proper input sanitization and the necessity of validating all user-provided data before storage and execution within web applications.