CVE-2024-3891 is a stored cross-site scripting (XSS) vulnerability classified under CWE-79, found in the Happy Addons for Elementor plugin for WordPress. This plugin extends Elementor’s functionality by adding widgets and design features. The vulnerability exists due to insufficient sanitization and escaping of HTML tags and attributes in widget content, allowing authenticated users with contributor-level permissions or higher to inject arbitrary JavaScript code into pages. When other users access these pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, or unauthorized actions within the context of the victim’s session. The vulnerability affects all versions up to and including 3.10.5. The CVSS 3.1 base score is 6.4, reflecting a medium severity with network attack vector, low attack complexity, requiring privileges but no user interaction, and impacting confidentiality and integrity with a scope change. No public exploits have been reported yet, but the vulnerability poses a significant risk in environments where multiple users have contributor or higher roles. The root cause is the failure to properly neutralize input during web page generation, specifically in widget attributes, which is a common vector for stored XSS in WordPress plugins. This vulnerability underscores the importance of rigorous input validation and output encoding in web applications, especially those that allow user-generated content to be rendered in HTML contexts.

The primary impact of this vulnerability is the potential for attackers with contributor-level access to inject persistent malicious scripts into WordPress pages. This can lead to partial confidentiality breaches, such as theft of session cookies or sensitive user data, and integrity violations, including unauthorized actions performed on behalf of other users. While availability is not directly affected, the exploitation can facilitate further attacks like privilege escalation or distribution of malware. Organizations relying on the Happy Addons for Elementor plugin, especially those with multiple content contributors, face increased risk of internal threat exploitation or compromised user accounts. The vulnerability could be leveraged to target site administrators or editors, potentially leading to site defacement, data leakage, or unauthorized content manipulation. Given WordPress’s widespread use globally, the impact can be significant for websites in sectors like media, education, e-commerce, and government that use this plugin. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits following public disclosure.

To mitigate this vulnerability, organizations should immediately update the Happy Addons for Elementor plugin to a patched version once released by the vendor. Until a patch is available, restrict contributor-level and higher permissions to trusted users only, minimizing the risk of malicious script injection. Implement additional input validation and output encoding at the application or web server level, such as using a Web Application Firewall (WAF) with rules to detect and block suspicious HTML or JavaScript payloads in widget content. Conduct regular audits of user-generated content for injected scripts or anomalies. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected pages. Educate content contributors about the risks of injecting untrusted HTML and enforce strict content guidelines. Monitor logs and user activity for unusual behavior indicative of exploitation attempts. Finally, maintain a robust backup and incident response plan to quickly recover from any compromise resulting from exploitation of this vulnerability.