CVE-2026-95864 in Themify Builder Plugin
Summary
by MITRE • 09/25/2026
The Themify Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'css[fonts]' Parameter in all versions up to, and including, 7.8.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The nonce required to reach the vulnerable endpoint is embedded in plain sight within the front-end page markup for all visitors, reducing the access control to a CSRF token rather than an authentication barrier and making the endpoint fully exploitable by unauthenticated attackers.
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Analysis
by VulDB Data Team • 09/25/2026
The Themify Builder plugin for WordPress contains a critical security vulnerability affecting all versions up to and including 7.8.1. This flaw is classified as a Stored Cross-Site Scripting (XSS) issue, specifically triggered through the css[fonts] parameter during the processing of user-supplied input. The root cause lies in insufficient input sanitization and output escaping mechanisms within the plugin's codebase. When an attacker submits malicious script content via this specific endpoint, the application fails to properly validate or encode the data before storing it in the database. Consequently, when other users subsequently view pages that utilize these stored values, the injected scripts are rendered by their browsers and executed automatically. This execution occurs within the context of the victim's session with the WordPress site, allowing the attacker to potentially hijack user sessions, deface websites, or redirect victims to malicious external sites.
A significant factor exacerbating the severity of this vulnerability is the lack of effective access control on the vulnerable endpoint. Typically, administrative actions in WordPress are protected by nonces (number used once) that require valid authentication and session verification. However, in this specific case, the nonce required to interact with the css[fonts] parameter is embedded directly within the front-end page markup accessible to all visitors without any restriction. This design flaw effectively reduces the security barrier from a robust authentication requirement to a simple Cross-Site Request Forgery (CSRF) token check. Since nonces are often predictable or easily retrievable by unauthenticated users through standard HTTP requests, attackers can craft valid-looking requests that bypass intended access controls. As a result, the vulnerability is fully exploitable by unauthenticated actors who do not need to possess any prior credentials or login privileges on the target WordPress installation.
The operational impact of this stored XSS vulnerability extends beyond immediate script execution. Because the malicious code is persisted in the database, it affects every user who accesses the compromised page, leading to a widespread compromise rather than an isolated incident. Attackers can leverage this capability to steal sensitive information such as administrative cookies or session tokens, facilitating unauthorized access to the WordPress dashboard. Furthermore, the ability to inject arbitrary web scripts allows for sophisticated phishing attacks where victims are redirected to fake login pages designed to capture credentials. The persistence of the payload means that remediation requires not only patching the code but also actively cleaning the database entries containing malicious content from affected installations.
From a classification perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific mechanism involving unauthenticated access via exposed nonces relates to CWE-352, or the Use of Cross-Site Request Forgery (CSRF) Protection Without Understanding Context. In terms of offensive security frameworks, this attack vector corresponds to MITRE ATT&CK technique T1059, specifically sub-technique 007 for Command and Scripting Interpreter: JavaScript. The exploitation path involves initial access through web application vulnerabilities followed by execution in the victim's browser environment.
To mitigate this vulnerability, site administrators must immediately update the Themify Builder plugin to a version later than 7.8.1 where these input validation and output escaping issues have been resolved. It is imperative that developers ensure all user-supplied data destined for storage or display undergoes rigorous sanitization using WordPress-specific functions such as sanitize_text_field or esc_html, depending on the context of usage. Additionally, access controls should be strictly enforced by verifying nonces against current user capabilities rather than relying solely on their presence in form fields. Regular security audits and penetration testing can help identify similar weaknesses in other plugins or custom code within the WordPress ecosystem to prevent future exploitation attempts.