CVE-2026-32542 in Fusion Builder Plugin
Summary
by MITRE • 03/25/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in ThemeFusion Fusion Builder fusion-builder allows Reflected XSS.This issue affects Fusion Builder: from n/a through < 3.15.0.
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Analysis
by VulDB Data Team • 04/01/2026
The vulnerability identified as CVE-2026-32542 represents a critical cross-site scripting flaw within the ThemeFusion Fusion Builder fusion-builder component, specifically affecting versions prior to 3.15.0. This reflected cross-site scripting vulnerability arises from inadequate input sanitization during web page generation processes, creating a significant security risk for WordPress websites utilizing this builder plugin. The flaw allows attackers to inject malicious scripts into web pages viewed by other users, potentially compromising user sessions and enabling unauthorized actions on behalf of victims.
The technical implementation of this vulnerability stems from improper neutralization of user-supplied input parameters that are subsequently reflected back to users within the generated web pages. When Fusion Builder processes certain input values without adequate sanitization or encoding, malicious payloads can be executed in the context of a victim's browser. This type of vulnerability falls under CWE-79, which specifically addresses improper neutralization of input during web page generation, making it a classic reflected XSS vector. The vulnerability manifests when user-provided parameters are directly incorporated into HTML output without appropriate context-specific escaping or encoding mechanisms.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, deface websites, steal sensitive user information, or redirect victims to malicious domains. Attackers can craft malicious URLs containing XSS payloads that, when clicked by an authenticated user, will execute scripts in the victim's browser context. This presents a significant risk to websites using Fusion Builder, particularly those with administrative users who may be targeted through social engineering attacks. The reflected nature of the vulnerability means that the malicious script is reflected off the web server rather than being stored, making it more difficult to detect through traditional security scanning approaches. According to ATT&CK framework, this vulnerability maps to T1531 - Establish Persistence, as successful exploitation could lead to persistent access through stolen session cookies or other credentials.
Mitigation strategies for CVE-2026-32542 primarily focus on upgrading to Fusion Builder version 3.15.0 or later, which contains the necessary patches to address the input sanitization issues. Administrators should also implement additional protective measures including input validation at multiple layers, output encoding for all dynamic content, and regular security auditing of plugin components. The remediation process should include comprehensive testing to ensure that the upgrade does not introduce compatibility issues with existing website functionality. Security professionals should monitor for exploitation attempts through web application firewalls and implement proper logging mechanisms to detect potential attack patterns. Organizations utilizing Fusion Builder should also consider implementing Content Security Policy headers to provide additional protection against XSS attacks, though this serves as a supplementary defense rather than a complete solution to the underlying vulnerability.