CVE-2024-37536 in Easy Custom Code Plugin
Summary
by MITRE • 07/21/2024
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Web357 Easy Custom Code (LESS/CSS/JS) – Live editing allows Stored XSS.This issue affects Easy Custom Code (LESS/CSS/JS) – Live editing: from n/a through 1.0.8.
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Analysis
by VulDB Data Team • 03/17/2025
This vulnerability represents a critical cross-site scripting flaw that exploits improper input sanitization within the Web357 Easy Custom Code plugin for WordPress. The weakness specifically manifests in the live editing functionality that permits users to input custom LESS/CSS/JS code directly into web pages. The vulnerability is classified as a stored XSS attack vector because malicious scripts entered through the custom code interface are permanently stored on the server and subsequently executed whenever affected pages are loaded by other users. This type of vulnerability falls under CWE-79 which defines improper neutralization of input during web page generation as a fundamental weakness in web application security. The flaw exists in the plugin's handling of user-supplied content without adequate sanitization or output encoding mechanisms that would prevent malicious code from being interpreted as executable JavaScript by web browsers.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it provides attackers with the ability to execute arbitrary code within the context of affected websites. When users with appropriate privileges access pages containing malicious code, their browsers execute the injected scripts with the privileges of the logged-in user, potentially enabling session hijacking, data exfiltration, or privilege escalation attacks. This vulnerability directly maps to ATT&CK technique T1566 which describes the use of malicious code injection to gain unauthorized access to systems. The stored nature of the XSS means that even users who do not directly interact with the vulnerable interface can be compromised when they view pages containing the malicious code, making the attack surface significantly broader than typical reflected XSS scenarios. The vulnerability affects all versions from the initial release through version 1.0.8, indicating a persistent flaw in the plugin's codebase that was not adequately addressed during development cycles.
Mitigation strategies must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. The most effective immediate solution involves updating to the latest version of the Easy Custom Code plugin where the XSS vulnerability has been patched through proper input sanitization and output encoding. Administrators should also implement content security policies that restrict script execution within the affected web pages, providing an additional layer of defense against malicious code execution. Regular security audits of third-party plugins should be conducted to identify similar input validation weaknesses, with particular attention to any functionality that allows users to input raw code or HTML content. The vulnerability demonstrates the importance of following secure coding practices such as those outlined in the OWASP Top Ten, specifically addressing the need for proper input validation and output encoding to prevent XSS attacks. Organizations should also consider implementing web application firewalls that can detect and block suspicious code patterns commonly associated with XSS attempts, while maintaining regular monitoring of plugin updates and security advisories from the WordPress security team to ensure comprehensive protection against emerging threats.