CVE-2025-58784 is a stored Cross-site Scripting (XSS) vulnerability identified in the ARI Fancy Lightbox plugin developed by arisoft, affecting versions up to and including 1.4.0. The vulnerability arises from improper neutralization of user input during web page generation, classified under CWE-79. Stored XSS means that malicious scripts injected by an attacker are permanently stored on the target server (e.g., in a database or persistent storage) and subsequently served to users without proper sanitization or encoding. When a victim loads the affected page, the malicious script executes in their browser context, potentially leading to session hijacking, credential theft, defacement, or redirection to malicious sites. The CVSS v3.1 base score is 6.5 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), user interaction (UI:R), scope changed (S:C), and low impact on confidentiality, integrity, and availability (C:L/I:L/A:L). This suggests that exploitation requires an attacker with some level of authenticated access and user interaction to trigger the payload, but the vulnerability can affect resources beyond the initially vulnerable component (scope changed). No patches or known exploits in the wild are reported as of the publication date (September 5, 2025). The plugin is commonly used to display images and media in a lightbox overlay on websites, often integrated into content management systems or custom web applications.

For European organizations, this vulnerability poses a moderate risk primarily to websites using the ARI Fancy Lightbox plugin. Exploitation could lead to unauthorized script execution in users' browsers, enabling attackers to steal session cookies, perform actions on behalf of users, or deliver further malware. This can compromise user trust, lead to data breaches involving personal data (potentially violating GDPR), and damage brand reputation. Since the vulnerability requires some level of authenticated access and user interaction, the risk is somewhat mitigated but still significant in environments with many users or where attackers can create accounts. Organizations in sectors with high web presence such as e-commerce, media, education, and government portals are particularly vulnerable. The scope change in the CVSS vector indicates that the impact could extend beyond the immediate plugin, potentially affecting other components or user sessions. The absence of known exploits suggests a window of opportunity for proactive mitigation before widespread attacks occur.

1. Immediate mitigation involves updating the ARI Fancy Lightbox plugin to a patched version once available. Since no patch links are currently provided, organizations should monitor vendor advisories closely. 2. Implement strict input validation and output encoding on all user-supplied data, especially where the plugin accepts input for display. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 4. Conduct thorough code reviews and penetration testing focused on XSS vulnerabilities in web applications using this plugin. 5. Limit user privileges to the minimum necessary to reduce the risk posed by the requirement for authenticated access. 6. Educate users to be cautious about interacting with unexpected or suspicious content, as user interaction is required for exploitation. 7. Consider deploying Web Application Firewalls (WAFs) with rules tuned to detect and block XSS payloads targeting this plugin. 8. Monitor web logs and user activity for unusual behavior that may indicate exploitation attempts.