CVE-2023-53928 is a stored cross-site scripting vulnerability found in PHPFusion version 9.10.30, a popular PHP-based content management system. The vulnerability resides in the file manager module, where it improperly neutralizes input during web page generation. Specifically, it allows attackers to upload SVG files containing embedded JavaScript within <script> tags. When these SVG files are viewed by users through the web interface, the embedded JavaScript executes in the context of the victim’s browser. This can enable attackers to steal session cookies, perform actions on behalf of the user, or conduct other client-side attacks such as redirecting users or delivering malware. The vulnerability requires the attacker to have low privileges (PR:L) to upload files, and user interaction (UI:P) is necessary to trigger the malicious script by viewing the SVG. The attack vector is network-based (AV:N), and no authentication bypass is involved. The vulnerability impacts confidentiality and integrity of user sessions but does not directly affect availability. The CVSS 4.0 score of 5.1 reflects a medium severity, considering the ease of exploitation and the limited scope of impact. No public exploits have been reported yet, but the presence of this vulnerability in a widely used CMS component makes it a notable risk. The lack of official patches or mitigation links in the provided data suggests that organizations must implement interim controls while awaiting vendor updates.

For European organizations, this vulnerability poses a risk primarily to web applications running PHPFusion 9.10.30, especially those that allow user-uploaded SVG files via the file manager. Successful exploitation can lead to session hijacking, enabling attackers to impersonate legitimate users and potentially escalate privileges or access sensitive data. This can compromise the confidentiality and integrity of user accounts and data. Organizations with public-facing websites or intranet portals using PHPFusion are at risk of client-side attacks that may damage reputation, lead to data breaches, or facilitate further network penetration. The impact is heightened in sectors with strict data protection regulations such as GDPR, where session theft or data exposure can result in regulatory penalties. Although no availability impact is expected, the indirect consequences of compromised user accounts can disrupt business operations and trust. The medium severity rating indicates that while the threat is not critical, it should not be ignored, especially in environments with high-value targets or sensitive user data.

1. Immediately restrict or disable SVG file uploads in the PHPFusion file manager until a vendor patch is available. 2. Implement strict server-side validation and sanitization of uploaded SVG files to remove or block embedded scripts. 3. Use Content Security Policy (CSP) headers to restrict execution of inline scripts and limit the domains from which scripts can be loaded, mitigating the impact of XSS. 4. Enforce least privilege access controls to limit who can upload files, reducing the risk of malicious uploads. 5. Educate users to avoid opening suspicious SVG files or links within the affected application. 6. Monitor web server logs and application activity for unusual file uploads or access patterns. 7. Keep PHPFusion installations updated and subscribe to vendor security advisories for timely patching. 8. Consider deploying Web Application Firewalls (WAF) with rules to detect and block malicious SVG payloads. 9. Conduct regular security assessments and penetration tests focusing on file upload functionalities. 10. If possible, isolate the file manager component or restrict access to trusted users only.