CVE-2025-57205 is a Stored Cross-Site Scripting (XSS) vulnerability affecting iNiLabs School Express (SMS Express) version 6.2. The flaw exists in the content-management features accessible to authenticated administrative users, specifically in the POSTed editor parameters submitted to the /posts/edit/{id} endpoint and similarly in Notice and Pages editors. Due to insufficient input sanitization and lack of proper output encoding, malicious HTML or JavaScript payloads can be injected and stored within the application. When other users subsequently access the compromised content, the malicious scripts execute in their browsers. This vulnerability enables an authenticated attacker to execute arbitrary JavaScript in the context of other users, potentially leading to session hijacking, privilege escalation, data exfiltration, or even administrative account takeover. The absence of a restrictive Content Security Policy (CSP) or effective filtering mechanisms exacerbates the risk, as there are no additional layers of defense to prevent or mitigate script execution. The vulnerability requires the attacker to have authenticated access with at least limited privileges (PR:L) and some user interaction (UI:R) to exploit, but the scope is considered changed (S:C) because the attack can affect other users beyond the attacker. The CVSS score of 5.4 (medium severity) reflects moderate impact on confidentiality and integrity, with no direct impact on availability. No known public exploits are reported yet, and no patches have been linked, indicating that organizations using this software should prioritize remediation once available.

For European organizations, especially educational institutions and administrative bodies using iNiLabs School Express 6.2, this vulnerability poses a significant risk. Exploitation could allow attackers to hijack sessions of administrative or other privileged users, leading to unauthorized access to sensitive student data, internal communications, or administrative controls. This could result in data breaches violating GDPR requirements, reputational damage, and potential regulatory penalties. The ability to escalate privileges or take over administrative accounts could further compromise the integrity of the school management system, disrupting operations and exposing confidential information. Given the collaborative nature of school management platforms, the spread of malicious scripts to multiple users increases the attack surface. The lack of CSP enforcement means that even well-configured browsers may not prevent exploitation. Although exploitation requires authenticated access, insider threats or compromised credentials could facilitate attacks. The medium severity rating suggests a moderate but tangible risk that should not be underestimated in environments handling personal data and critical educational workflows.

1. Immediate mitigation should include restricting administrative access to trusted personnel only and enforcing strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. 2. Implement strict input validation and output encoding on all content-management inputs, especially the POSTed editor parameters, to sanitize HTML and JavaScript content before storage and rendering. 3. Deploy a robust Content Security Policy (CSP) that restricts the execution of inline scripts and only allows trusted sources for scripts and other active content. 4. Monitor logs and user activity for unusual behavior indicative of exploitation attempts, such as unexpected content changes or script injections. 5. Until an official patch is available, consider disabling or limiting the use of the vulnerable content-management features or endpoints if feasible. 6. Educate administrative users about the risks of XSS and safe content management practices. 7. Regularly update and patch the SMS Express software once vendor fixes are released. 8. Conduct security assessments and penetration testing focused on web application vulnerabilities to identify and remediate similar issues proactively.