CVE-2025-57205 is a Stored Cross-Site Scripting (XSS) vulnerability affecting iNiLabs School Express (SMS Express) version 6.2. The vulnerability exists within the content-management features accessible to authenticated administrative users, specifically in the POSTed editor parameters submitted to the /posts/edit/{id} endpoint, as well as similar endpoints for Notices and Pages editors. Due to insufficient input sanitization and lack of proper output encoding, malicious HTML or JavaScript payloads can be injected and stored persistently in the application’s database. When other users access the affected content, the malicious scripts execute in their browsers within the context of the vulnerable application. This can lead to serious security consequences including session hijacking, privilege escalation, data exfiltration, and even administrative account takeover. The risk is exacerbated by the absence of a restrictive Content Security Policy (CSP) or other effective filtering mechanisms that could mitigate the impact of such injected scripts. Although exploitation requires authentication as an admin user, the stored nature of the XSS means that any user viewing the compromised content is at risk. No CVSS score has been assigned yet, and there are no known exploits in the wild at the time of publication. The vulnerability highlights a critical failure in input validation and output encoding in a system that manages sensitive school administrative data, potentially exposing confidential student and staff information and administrative controls to attackers.

For European organizations, particularly educational institutions using iNiLabs School Express 6.2, this vulnerability poses significant risks. Exploitation could allow attackers with admin credentials to embed malicious scripts that compromise the confidentiality and integrity of sensitive student records, staff information, and administrative data. The ability to hijack sessions or escalate privileges could lead to unauthorized access to protected systems and data breaches. Additionally, the compromise of administrative accounts could disrupt school operations or enable further lateral movement within the network. Given the GDPR regulations in Europe, any data breach resulting from this vulnerability could lead to severe legal and financial penalties. The lack of a restrictive CSP increases the likelihood that injected scripts will execute successfully in users’ browsers, amplifying the threat. Although exploitation requires authenticated admin access, insider threats or compromised admin credentials could facilitate attacks. The persistent nature of stored XSS means that even non-admin users accessing affected content are at risk, broadening the scope of impact within the organization.

To mitigate this vulnerability, organizations should immediately implement strict input validation and output encoding on all content-management inputs, especially those related to posts, notices, and pages editors. Employing a robust whitelist-based sanitization library that removes or encodes potentially dangerous HTML and JavaScript is critical. Additionally, deploying a strong Content Security Policy (CSP) that restricts script execution sources can significantly reduce the risk of successful XSS exploitation. Organizations should also enforce the principle of least privilege, ensuring that only necessary users have administrative access to content management features. Regularly auditing admin accounts and monitoring for suspicious activity can help detect potential exploitation attempts. Applying any available patches or updates from the vendor as soon as they are released is essential. If patches are not yet available, consider temporarily restricting access to the vulnerable endpoints or disabling the affected content-management features. Educating administrators about phishing and credential security can reduce the risk of credential compromise that would enable exploitation. Finally, implementing web application firewalls (WAFs) with rules designed to detect and block XSS payloads can provide an additional layer of defense.