CVE-2025-66066 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the EnvoThemes Envo Extra plugin, affecting all versions up to and including 1.9.11. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing malicious scripts to be stored persistently on the server and executed in the context of users' browsers when they access the affected pages. This type of vulnerability is particularly dangerous because the malicious payload is served from a trusted domain, increasing the likelihood of successful exploitation. The CVSS v3.1 score of 6.1 reflects a medium severity, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but requiring user interaction to trigger the malicious script. The scope is changed, indicating that the vulnerability affects components beyond the initially vulnerable module. The impact includes limited confidentiality and integrity loss, such as theft of session cookies, user impersonation, or unauthorized actions performed on behalf of the user. Availability is not impacted. No public exploits have been reported yet, but the presence of this vulnerability in a widely used WordPress plugin makes it a potential target for attackers aiming to compromise websites and their visitors. The lack of an official patch link suggests that users should monitor vendor communications closely for updates.

For European organizations, especially those relying on WordPress websites enhanced with the Envo Extra plugin, this vulnerability poses a risk of client-side attacks that can lead to session hijacking, defacement, or unauthorized actions performed by attackers impersonating legitimate users. This can damage organizational reputation, lead to data leakage, and potentially facilitate further attacks such as phishing or malware distribution. The medium severity indicates that while the impact is not critical, it is significant enough to warrant prompt attention. Organizations in sectors with high web presence, such as e-commerce, media, and government services, are particularly at risk. The exploitation requires user interaction, which means targeted phishing or social engineering campaigns could be used to maximize impact. Given the interconnected nature of European digital infrastructure, successful exploitation could also affect supply chain partners and customers.

1. Monitor EnvoThemes official channels for patches addressing CVE-2025-66066 and apply updates immediately upon release. 2. In the absence of patches, implement strict input validation and sanitization on all user inputs that are rendered on web pages, ensuring that scripts and HTML tags are properly escaped or removed. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the risk of XSS exploitation. 4. Use Web Application Firewalls (WAFs) with rules designed to detect and block XSS payloads targeting Envo Extra plugin endpoints. 5. Conduct regular security audits and penetration testing focusing on web application input handling and output encoding. 6. Educate users about the risks of interacting with suspicious links or content that could trigger XSS attacks. 7. Consider disabling or replacing the Envo Extra plugin if immediate patching is not feasible and the plugin is not critical to business operations.