CVE-2023-53884 is a stored cross-site scripting vulnerability affecting Webedition CMS version 2.9.8.8. The vulnerability arises from improper neutralization of input during web page generation, specifically allowing authenticated users to upload SVG files that contain embedded JavaScript code. SVG files are vector graphics files that can include script elements, and in this case, the CMS does not sanitize or validate the SVG content properly before storing and rendering it. An attacker with authenticated access can upload a crafted SVG file through the media upload feature. When other users view the page or media library containing the malicious SVG, the embedded JavaScript executes in their browsers. This can lead to session hijacking, credential theft, unauthorized actions, or other malicious activities typical of XSS attacks. The vulnerability requires the attacker to have at least authenticated user privileges, and victim users must interact by viewing the malicious SVG file. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required for exploitation (though authentication is needed), user interaction required, and low impact on confidentiality and integrity but limited impact on availability. No public exploit code or active exploitation has been reported to date. The vulnerability highlights a common weakness in web applications that accept SVG uploads without proper sanitization, emphasizing the need for strict input validation and output encoding.

For European organizations using Webedition CMS 2.9.8.8, this vulnerability poses a risk of client-side script execution leading to session hijacking, theft of sensitive information, or unauthorized actions performed in the context of legitimate users. This can compromise user accounts, internal communications, and potentially lead to further network compromise if attackers leverage stolen credentials or session tokens. The impact is particularly significant for organizations with many authenticated users accessing the CMS, such as media companies, government agencies, or enterprises managing public-facing websites. The stored nature of the XSS means the malicious payload persists and can affect multiple users over time. Although the CVSS score is medium, the ease of uploading malicious SVGs by authenticated users and the potential for lateral movement within an organization increase the threat. Additionally, the lack of known exploits in the wild suggests an opportunity for proactive mitigation before attackers develop weaponized payloads. Failure to address this vulnerability could lead to reputational damage, data breaches, and regulatory penalties under GDPR if personal data is compromised.

1. Upgrade Webedition CMS to a version where this vulnerability is patched once available. Monitor vendor advisories for official patches. 2. Implement strict server-side validation and sanitization of SVG files before allowing uploads, removing or neutralizing any embedded scripts or potentially dangerous elements. 3. Restrict media upload permissions to only trusted users and roles to minimize the risk of malicious file uploads. 4. Employ Content Security Policy (CSP) headers to restrict script execution sources and reduce the impact of XSS attacks. 5. Regularly audit uploaded media files for suspicious content using automated scanning tools that detect embedded scripts in SVGs. 6. Educate users about the risks of interacting with untrusted media files and encourage reporting of suspicious content. 7. Monitor web server and application logs for unusual activity related to media uploads or script execution. 8. Consider disabling SVG uploads if not strictly necessary or convert SVGs to safer formats after upload. 9. Use web application firewalls (WAFs) configured to detect and block XSS payloads in HTTP requests and responses. 10. Conduct periodic security assessments and penetration tests focusing on file upload functionalities.