CVE-2025-55816 identifies a Cross Site Scripting (XSS) vulnerability in HotelDruid versions 3.0.7 and earlier, specifically within the /modifica_app.php file. XSS vulnerabilities arise when an application does not properly sanitize user-supplied input, allowing attackers to inject malicious scripts that execute in the context of other users' browsers. This vulnerability is classified under CWE-79, indicating improper neutralization of input during web page generation. The CVSS 3.1 base score is 6.1, with vector AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, meaning the attack can be launched remotely over the network with low attack complexity, no privileges required, but requires user interaction (e.g., clicking a crafted link). The scope is changed, indicating that exploitation can affect resources beyond the vulnerable component. The impact affects confidentiality and integrity partially, allowing attackers to potentially steal session cookies, perform actions on behalf of users, or manipulate displayed content. No patches or exploits are currently publicly available, but the vulnerability is published and should be addressed proactively. HotelDruid is a hotel management system used primarily by small to medium-sized hospitality businesses to manage bookings, clients, and operations. The vulnerable script likely handles modification of application data, making it a critical point for input validation. Failure to sanitize inputs in this module exposes users to script injection attacks that can compromise user sessions or redirect users to malicious sites.

For European organizations, especially those in the hospitality sector using HotelDruid, this vulnerability poses a risk of client-side attacks that can lead to theft of session tokens, unauthorized actions, or defacement of web interfaces. Confidentiality of user data, including personal and booking information, could be partially compromised. Integrity of displayed data or user actions may be affected, potentially leading to fraudulent bookings or unauthorized modifications. Although availability is not impacted, the reputational damage and potential regulatory consequences under GDPR for data breaches could be significant. Small and medium enterprises in countries with large tourism industries may be particularly vulnerable due to limited cybersecurity resources. The vulnerability could also be leveraged in targeted phishing campaigns exploiting the trust in hotel management portals. Since no known exploits are in the wild, timely mitigation can prevent exploitation. Failure to address this vulnerability could lead to compliance issues and loss of customer trust.

1. Implement strict input validation and sanitization on all user-supplied data in the /modifica_app.php file, ensuring that scripts or HTML tags are properly encoded or removed. 2. Apply output encoding on all dynamic content rendered in the affected module to prevent script execution. 3. Restrict user input fields to accept only expected data types and lengths, employing whitelisting where possible. 4. Upgrade HotelDruid to the latest version once a patch is released; monitor vendor advisories for updates. 5. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in the web application. 6. Conduct regular security audits and penetration testing focusing on input handling in web modules. 7. Educate staff and users about the risks of clicking unknown links and recognizing phishing attempts. 8. Monitor web server logs for suspicious requests targeting /modifica_app.php or unusual input patterns. 9. If patching is delayed, consider implementing web application firewall (WAF) rules to detect and block XSS payloads targeting this endpoint. 10. Ensure secure session management to limit the impact of stolen session tokens.