CVE-2026-39739 in Ultimate Addons for Elementor Plugin
Summary
by MITRE • 10/30/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Brainstorm Force Ultimate Addons for Elementor - Lite header-footer-elementor allows Stored XSS.This issue affects Ultimate Addons for Elementor - Lite: from n/a through 2.9.5.
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Analysis
by VulDB Data Team • 10/30/2026
The identified security flaw represents a classic instance of Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting or XSS. Specifically, this vulnerability is classified under the CWE-79 standard and manifests within the header-footer-elementor component of the Brainstorm Force Ultimate Addons for Elementor - Lite plugin. The nature of this flaw allows an attacker to inject malicious scripts into web pages viewed by other users, leading to a Stored Cross-Site Scripting scenario where the payload is permanently saved on the target server rather than being executed only in a transient context like reflected XSS.
The technical root cause lies in the insufficient validation and sanitization of user-supplied input before it is rendered within the HTML output generated by the plugin. When an authenticated user, typically one with permissions to edit site headers or footers via Elementor, provides data that contains executable JavaScript code, the application fails to properly escape special characters such as quotes, ampersands, and angle brackets. Consequently, when another user visits a page utilizing this compromised header or footer template, their browser interprets the injected script as legitimate content from the trusted domain. This bypasses same-origin policy protections because the malicious code originates from the site itself in the eyes of the victim's browser.
The operational impact of this Stored XSS vulnerability is significant and multifaceted. Attackers can exploit this flaw to steal session cookies, which may lead to account takeover if high-privilege accounts are compromised. Furthermore, the injected scripts can perform actions on behalf of the victim without their knowledge or consent, such as changing site settings, defacing the website interface, or redirecting users to malicious phishing sites. In enterprise environments, this could facilitate further lateral movement within a network by using the victim's authenticated session to access internal resources that are not publicly exposed but are accessible through legitimate administrative interfaces.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.007, which covers JavaScript execution in web browsers. The attack vector typically involves social engineering or direct exploitation by a user who has the ability to modify header and footer elements within the WordPress dashboard. Once the malicious code is stored, it persists until manually removed from the database or plugin configuration, creating a long-term risk for all visitors to the affected site. This persistence distinguishes it from temporary vulnerabilities that require repeated interaction with a specific input field on each visit.
Mitigation strategies must address both immediate remediation and long-term security hygiene. The primary solution is to upgrade Brainstorm Force Ultimate Addons for Elementor - Lite to version 2.9.6 or later, where the developers have implemented proper output encoding and context-aware sanitization techniques. For sites unable to update immediately due to compatibility concerns with other plugins, temporary workarounds include restricting access to header and footer editing capabilities to only highly trusted administrators rather than editors or authors who may be more susceptible to social engineering attacks. Additionally, implementing a Content Security Policy (CSP) can help mitigate the impact of successful XSS attempts by restricting the sources from which scripts are allowed to execute, thereby preventing the injection of arbitrary code even if it reaches the browser.
Security teams should also conduct regular audits of third-party plugins used in their WordPress infrastructure, ensuring that they adhere to secure coding standards such as those outlined in OWASP guidelines for input validation and output encoding. Monitoring server logs for unusual patterns of script execution or unexpected changes to header and footer configurations can aid in early detection of exploitation attempts. By combining timely software updates with robust access controls and defensive browser policies, organizations can significantly reduce the risk posed by this class of web application vulnerabilities.