CVE-2025-41057 is a stored Cross-Site Scripting (XSS) vulnerability identified in version 4.0.5 of the appRain CMF (Content Management Framework). The vulnerability arises from improper neutralization of user input during web page generation, specifically within the parameters 'data[Addon][layouts]' and 'data[Addon][layouts_except]' in the endpoint /apprain/developer/addons/update/rich_text_editor. Because these parameters are not properly validated or sanitized, an authenticated attacker can inject malicious scripts that are stored on the server and subsequently executed in the context of other users' browsers when they access affected pages. This type of stored XSS can lead to session hijacking, privilege escalation, defacement, or distribution of malware. The vulnerability requires low privileges (authenticated user) and user interaction (victim must load the malicious content), but does not require advanced attack complexity or special conditions. The CVSS v4.0 score is 5.1 (medium severity), reflecting network attack vector, low attack complexity, no privileges required beyond authentication, and limited scope impact. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability is cataloged under CWE-79, which is a common and well-understood web application security issue related to improper input validation and output encoding.

For European organizations using appRain CMF 4.0.5, this vulnerability poses a moderate risk. Stored XSS can compromise the confidentiality and integrity of user sessions and data, potentially allowing attackers to impersonate legitimate users, steal sensitive information, or perform unauthorized actions within the application. This can lead to data breaches, reputational damage, and regulatory non-compliance, especially under GDPR requirements for protecting personal data. The impact is heightened in sectors where appRain CMF is used to manage critical content or internal tools, such as government portals, educational institutions, or enterprises with European operations. Since exploitation requires authenticated access, insider threats or compromised user accounts are the most likely attack vectors. The lack of known exploits reduces immediate risk, but the presence of this vulnerability in a web-facing component means it could be targeted in the future, especially if attackers gain credentials through phishing or other means.

European organizations should implement the following specific mitigations: 1) Immediately audit and restrict user privileges to minimize the number of users who can access the vulnerable endpoint. 2) Apply strict input validation and output encoding on the 'data[Addon][layouts]' and 'data[Addon][layouts_except]' parameters, ideally by updating to a patched version of appRain CMF once available. 3) Implement Web Application Firewall (WAF) rules to detect and block suspicious payloads targeting these parameters. 4) Conduct regular security reviews and penetration testing focusing on authenticated user input vectors. 5) Educate users about phishing and credential security to reduce the risk of account compromise. 6) Monitor logs for unusual activity around the /apprain/developer/addons/update/rich_text_editor endpoint. 7) If patching is not immediately possible, consider temporarily disabling or restricting access to the affected functionality. These steps go beyond generic advice by focusing on the specific vulnerable parameters and the authenticated nature of the exploit.