CVE-2025-41042 is a stored Cross-site Scripting (XSS) vulnerability identified in appRain CMF version 4.0.5. The vulnerability arises from improper neutralization of user input during web page generation, specifically within the parameters 'data[Option][message]', 'data[Option][subject]', and 'data[Option][templatetype]' in the endpoint /apprain/information/manage/emailtemplate/add. Because these inputs are not properly validated or sanitized, an authenticated user can inject malicious scripts that are stored on the server and later executed in the context of other users' browsers when they access the affected pages. This type of vulnerability is classified under CWE-79, which covers improper input validation leading to XSS attacks. The CVSS 4.0 base score for this vulnerability is 5.1 (medium severity), with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:L - low privileges), and user interaction required (UI:P). The vulnerability does not impact confidentiality, integrity, or availability directly but can be leveraged to execute arbitrary scripts in victim browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in April 2025 and published in September 2025 by INCIBE. The affected product, appRain CMF, is a content management framework used to build and manage web applications, and the vulnerability specifically affects version 4.0.5. Given the stored nature of the XSS, the impact can be persistent and affect multiple users once exploited.

For European organizations using appRain CMF 4.0.5, this vulnerability poses a risk primarily to web application security and user trust. Exploitation could allow attackers to execute malicious scripts in the browsers of authenticated users, potentially leading to theft of session cookies, user credentials, or the execution of unauthorized actions within the application. This can result in unauthorized data access, privilege escalation, or further compromise of internal systems. Since appRain CMF is used to manage web content, organizations relying on it for customer-facing or internal portals could face reputational damage and operational disruptions if attackers leverage this vulnerability. The medium CVSS score reflects moderate risk, but the requirement for authenticated access and user interaction somewhat limits the attack surface. However, in environments where multiple users have access to the vulnerable functionality, the risk of lateral movement and broader compromise increases. European organizations in sectors such as government, finance, and critical infrastructure that use appRain CMF may be particularly concerned due to the sensitivity of their data and regulatory requirements like GDPR, which mandate protection of personal data and timely remediation of vulnerabilities.

1. Immediate mitigation should include restricting access to the vulnerable endpoint (/apprain/information/manage/emailtemplate/add) to only trusted administrators until a patch is available. 2. Implement strict input validation and output encoding on the affected parameters ('data[Option][message]', 'data[Option][subject]', 'data[Option][templatetype]') to neutralize any malicious scripts. This can be done by applying context-aware encoding (e.g., HTML entity encoding) before rendering user input in the web pages. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers, reducing the impact of potential XSS payloads. 4. Monitor logs for unusual activity or injection attempts targeting the vulnerable parameters. 5. Educate users about phishing and social engineering risks that could be combined with XSS attacks. 6. Once available, promptly apply official patches or updates from appRain to remediate the vulnerability. 7. Conduct a thorough security review of all user input handling in the application to identify and fix similar issues proactively. 8. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block XSS payloads targeting the affected endpoints.