CVE-2025-41054 is a stored Cross-site Scripting (XSS) vulnerability identified in appRain CMF version 4.0.5, a content management framework. The vulnerability arises due to improper neutralization of user input during web page generation, specifically in the parameters 'data[Addon][layouts]' and 'data[Addon][layouts_except]' within the endpoint /apprain/developer/addons/update/cycle. Because these parameters are not properly validated or sanitized, an authenticated user can inject malicious scripts that are stored on the server and subsequently executed in the browsers of users who access the affected pages. This type of stored XSS can lead to session hijacking, defacement, or redirection to malicious sites. The CVSS 4.0 base score is 5.1 (medium severity), reflecting that the attack vector is network-based, requires low attack complexity, no privileges, but does require user interaction and some privileges (PR:L) to exploit. The vulnerability does not impact confidentiality, integrity, or availability directly but can be leveraged to compromise user sessions or perform unauthorized actions through the victim's browser. No known exploits are currently in the wild, and no patches have been published yet. The vulnerability was reserved in April 2025 and published in September 2025 by INCIBE, indicating recent discovery and disclosure.

For European organizations using appRain CMF 4.0.5, this vulnerability poses a risk primarily to web application security and user trust. Stored XSS can allow attackers to execute arbitrary JavaScript in the context of the victim's browser, potentially leading to theft of session cookies, user credentials, or performing actions on behalf of users with their privileges. This can result in unauthorized access to sensitive data or administrative functions within the CMS, leading to data leakage or defacement of websites. Given that exploitation requires authenticated access, insider threats or compromised accounts are the most likely vectors. The impact on confidentiality and integrity is moderate, while availability is less affected. For organizations in sectors such as government, finance, healthcare, or e-commerce, where appRain CMF might be used for public-facing or internal portals, the reputational damage and regulatory implications under GDPR could be significant if personal data is exposed or manipulated. Additionally, the need for user interaction and some privileges limits the ease of exploitation but does not eliminate risk, especially in environments with weak access controls or phishing susceptibility.

1. Immediate mitigation should include restricting access to the vulnerable endpoint (/apprain/developer/addons/update/cycle) to trusted administrators only, using network-level controls such as IP whitelisting or VPN access. 2. Implement strict input validation and output encoding on the 'data[Addon][layouts]' and 'data[Addon][layouts_except]' parameters to neutralize any injected scripts. This can be done by applying context-aware encoding (e.g., HTML entity encoding) and sanitization libraries that remove or escape potentially dangerous characters. 3. Enforce the principle of least privilege by reviewing user roles and permissions to minimize the number of users who can access the vulnerable functionality. 4. Monitor logs for suspicious activity related to these parameters or unusual POST requests to the affected endpoint. 5. Educate users and administrators about phishing and social engineering risks to reduce the chance of credential compromise. 6. As no official patch is available yet, consider deploying a Web Application Firewall (WAF) with custom rules to detect and block malicious payloads targeting these parameters. 7. Plan for prompt application of vendor patches once released and conduct thorough testing to ensure the vulnerability is remediated.