CVE-2025-66067 is a DOM-based Cross-site Scripting (XSS) vulnerability identified in the Funnel Builder plugin by FunnelKit, affecting versions up to and including 3.13.1.2. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, which allows malicious scripts to be injected and executed within the context of a victim's browser. This type of XSS is client-side, meaning the malicious payload is executed in the Document Object Model (DOM) after the page loads, often triggered by user interaction such as clicking a crafted URL or interacting with a manipulated page element. The CVSS v3.1 score of 5.4 reflects a medium severity, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but requiring user interaction. The impact primarily affects confidentiality and integrity, as attackers can steal sensitive information like cookies or session tokens, or perform actions on behalf of the user. Availability is not impacted. No known public exploits or active exploitation campaigns have been reported to date. The vulnerability affects a popular WordPress funnel-building plugin widely used in marketing and e-commerce sites, making it a relevant concern for organizations leveraging FunnelKit for customer engagement and sales funnels. The absence of a patch link suggests that a fix may be pending or recently released, emphasizing the need for vigilance and timely updates.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Funnel Builder by FunnelKit for their online marketing and sales funnels. Exploitation could lead to theft of user credentials, session hijacking, or unauthorized actions performed in the context of authenticated users, potentially compromising customer data and trust. This could result in regulatory repercussions under GDPR due to data breaches involving personal information. Additionally, compromised websites might suffer reputational damage and loss of business. Since FunnelKit is integrated into WordPress environments, which are prevalent across Europe, the attack surface is considerable. However, the requirement for user interaction limits automated mass exploitation, somewhat reducing the risk. The vulnerability does not affect system availability, so denial-of-service is not a concern here. Overall, the threat could facilitate targeted attacks against marketing platforms, undermining confidentiality and integrity of user sessions and data.

European organizations should implement a multi-layered mitigation strategy: 1) Monitor FunnelKit vendor communications closely and apply security patches immediately once released to address CVE-2025-66067. 2) Until patches are available, implement strict input validation and sanitization on all user-supplied data within the FunnelKit environment, potentially using web application firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting FunnelKit endpoints. 3) Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 4) Educate users and administrators about the risks of clicking untrusted links or interacting with suspicious content related to FunnelKit-powered pages. 5) Regularly audit and monitor web application logs for anomalous activity indicative of attempted XSS exploitation. 6) Consider isolating FunnelKit functionality or limiting its exposure to authenticated users only, reducing the attack surface. 7) Employ security plugins or tools that can detect and remediate XSS vulnerabilities within WordPress environments. These targeted steps go beyond generic advice by focusing on the specific plugin and attack vector involved.