CVE-2023-53876 is a vulnerability identified in Creativeitem's Academy LMS version 6.1, involving an unrestricted file upload flaw specifically targeting the profile avatar upload functionality. Authenticated users can upload SVG files that contain embedded JavaScript code, which is executed when the SVG is rendered by other users, resulting in stored cross-site scripting (XSS). The vulnerability stems from inadequate validation and sanitization of uploaded files, allowing attackers to bypass file type restrictions by altering file extensions and embedding malicious scripts within SVG images. This stored XSS can be leveraged to hijack user sessions, steal cookies, perform actions on behalf of victims, or deliver further malware. The attack vector requires the attacker to be authenticated and involves some user interaction, such as viewing the malicious avatar. The CVSS 4.0 base score is 5.1, indicating a medium severity level due to network attack vector, low attack complexity, no privileges required beyond authentication, and partial impact on confidentiality and integrity. No public exploits have been reported yet, but the vulnerability poses a risk to organizations relying on Academy LMS for e-learning and training. The lack of patch links suggests that a fix may not yet be publicly available, emphasizing the need for interim mitigations.

For European organizations using Academy LMS 6.1, this vulnerability could lead to unauthorized script execution within the LMS environment, compromising user accounts and potentially exposing sensitive educational data. Stored XSS can facilitate session hijacking, credential theft, and unauthorized actions performed under the guise of legitimate users, undermining trust in the LMS platform. Given the widespread adoption of e-learning platforms in Europe, especially in educational institutions and corporate training, exploitation could disrupt learning activities and lead to data breaches. The requirement for authentication limits the attack surface but does not eliminate risk, as any legitimate user could exploit the flaw. The impact on confidentiality and integrity is moderate, while availability is unlikely to be directly affected. Organizations handling personal data of students and employees must consider GDPR implications if data is compromised. The absence of known exploits reduces immediate risk but does not preclude future attacks.

European organizations should implement strict server-side validation of uploaded files, ensuring only safe image formats are accepted and that SVG files are either disallowed or sanitized to remove executable content. Employing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting script execution contexts. Restrict avatar upload permissions to trusted users or administrators where feasible. Monitor and audit file uploads for suspicious content and implement web application firewalls (WAF) with rules targeting malicious SVG payloads. Encourage users to update to newer versions of Academy LMS once patches are released. In the interim, consider disabling the avatar upload feature or restricting it to non-SVG formats. Educate users about phishing and social engineering risks associated with malicious avatars. Regularly review and update security policies related to LMS usage and file uploads.