CVE-2023-53909 is a stored cross-site scripting vulnerability found in WBCE CMS version 1.6.1. The flaw exists due to improper neutralization of input during web page generation, specifically when handling SVG file uploads via the media manager component. Authenticated attackers can upload SVG files containing embedded JavaScript code to the endpoint /wbce/modules/elfinder/ef/php/connector.wbce.php. Because SVG files can contain script tags, the malicious JavaScript executes in the context of any user who views or accesses the uploaded SVG file, leading to stored XSS. This can allow attackers to perform actions such as stealing session cookies, performing actions on behalf of the victim, or delivering further malware payloads. The vulnerability requires the attacker to have authenticated access to the CMS to upload the malicious SVG, and victim users must interact with or view the uploaded file to trigger the exploit. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required beyond authentication, and user interaction required. The impact on confidentiality and integrity is low to limited, but the vulnerability can be leveraged for privilege escalation or lateral movement within an organization’s web infrastructure. No patches or known exploits are currently reported, but the vulnerability is publicly disclosed and should be addressed promptly.

For European organizations using WBCE CMS 1.6.1, this vulnerability poses a moderate risk. Attackers with authenticated access can upload malicious SVG files that execute JavaScript in the browsers of other users, potentially leading to session hijacking, unauthorized actions, or defacement of websites. This can damage organizational reputation, lead to data leakage, or enable further attacks within the network. Since WBCE CMS is a content management system, it is often used for managing websites and digital content, making the integrity and availability of these sites critical. The requirement for authenticated access limits the attack surface but insider threats or compromised credentials could be exploited. The vulnerability could also be used as a stepping stone for more advanced attacks targeting European organizations with sensitive or high-profile web presence. The medium severity suggests that while the immediate impact is limited, the potential for exploitation in targeted attacks exists.

European organizations should implement the following specific mitigations: 1) Immediately restrict upload permissions to trusted users only and audit existing uploaded SVG files for malicious content. 2) Disable or restrict SVG file uploads if not strictly necessary, or sanitize SVG files to remove script tags before allowing upload. 3) Apply strict Content Security Policy (CSP) headers to limit script execution from untrusted sources. 4) Upgrade WBCE CMS to a patched version once available or apply vendor-provided patches or workarounds. 5) Monitor web server logs and CMS activity for suspicious file uploads or access patterns. 6) Educate CMS users about the risks of uploading untrusted files and enforce strong authentication mechanisms to reduce the risk of compromised accounts. 7) Consider implementing web application firewalls (WAF) with rules to detect and block malicious SVG payloads. These targeted actions go beyond generic advice by focusing on controlling SVG uploads, sanitization, and monitoring specific to this vulnerability.