CVE-2025-55709 is a security vulnerability classified as CWE-79, which corresponds to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This specific vulnerability affects the Visual Composer Website Builder, a widely used WordPress plugin for creating and managing website content. The vulnerability allows an attacker to inject malicious scripts that are stored persistently (Stored XSS) within the website content generated by Visual Composer. When other users or administrators access the affected pages, the malicious script executes in their browsers, potentially leading to session hijacking, defacement, unauthorized actions, or redirection to malicious sites. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L) indicates that the attack can be performed remotely over the network, requires low attack complexity, requires privileges (PR:L) but only limited user interaction (UI:R), and impacts confidentiality, integrity, and availability to a limited extent but with scope change (S:C). The vulnerability is present in unspecified versions of Visual Composer Website Builder, with no patch currently available or linked. No known exploits are reported in the wild at this time. Stored XSS vulnerabilities are particularly dangerous because they can affect multiple users and persist until the malicious content is removed. The vulnerability arises from improper input sanitization or output encoding during web page generation, allowing malicious payloads to be embedded in the website content.

For European organizations using Visual Composer Website Builder, this vulnerability poses a significant risk to website security and user trust. Exploitation could lead to unauthorized access to user sessions, theft of sensitive information such as authentication tokens or personal data, and potential defacement or manipulation of website content. This can damage brand reputation, lead to regulatory non-compliance (e.g., GDPR violations due to data leakage), and disrupt business operations. Since Visual Composer is popular among small to medium enterprises and agencies for website creation, a wide range of sectors including e-commerce, professional services, and public sector entities could be affected. The scope change indicated by the CVSS vector means that the vulnerability could allow attackers to escalate privileges or affect users beyond the initially compromised context, increasing the potential impact. Additionally, the requirement for some privileges and user interaction suggests that attackers might need to compromise an account with limited permissions or trick a user into performing an action, which is feasible in many real-world scenarios. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after public disclosure.

European organizations should take proactive steps to mitigate this vulnerability. First, monitor official Visual Composer channels and security advisories for patches or updates addressing CVE-2025-55709 and apply them promptly once available. Until a patch is released, implement strict input validation and output encoding on all user-generated content fields within the website builder environment to prevent injection of malicious scripts. Employ Web Application Firewalls (WAFs) with custom rules to detect and block typical XSS payload patterns targeting Visual Composer endpoints. Conduct thorough security audits and penetration testing focusing on stored XSS vectors in the website content. Educate users and administrators about the risks of clicking on suspicious links or executing untrusted scripts. Limit privileges of user accounts interacting with the website builder to the minimum necessary to reduce the attack surface. Enable Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Regularly back up website content and configurations to enable quick restoration in case of compromise. Finally, consider deploying runtime application self-protection (RASP) solutions that can detect and block XSS attacks in real time.