CVE-2025-55816 is a security vulnerability classified as a Cross Site Scripting (XSS) flaw found in HotelDruid, a property management system widely used in the hospitality industry. The vulnerability exists in the /modifica_app.php file of HotelDruid version 3.0.7 and earlier. XSS vulnerabilities allow attackers to inject malicious client-side scripts into web pages viewed by other users. In this case, the vulnerability likely arises from insufficient input validation or improper output encoding in the affected PHP script, enabling attackers to craft specially crafted requests that embed malicious JavaScript code. When a victim accesses the compromised page, the injected script executes in their browser context, potentially allowing attackers to steal session cookies, perform actions on behalf of the user, or redirect users to malicious sites. Although no public exploits have been reported yet, the vulnerability is publicly disclosed and could be targeted by attackers, especially given the hospitality sector's attractiveness due to sensitive customer data and payment information. The absence of a CVSS score suggests the need for an independent severity assessment. The vulnerability does not require authentication or user interaction beyond visiting a malicious link or page, increasing its risk profile. HotelDruid is used internationally, including across Europe, where the hospitality industry is a critical economic sector. The vulnerability's exploitation could lead to data breaches, reputational damage, and financial losses for affected organizations.

For European organizations, particularly those in the hospitality and tourism sectors using HotelDruid, this XSS vulnerability could lead to significant impacts. Attackers exploiting this flaw can hijack user sessions, steal sensitive customer data such as personal identification and payment details, and perform unauthorized actions within the application. This can result in data breaches, regulatory non-compliance (e.g., GDPR violations), financial fraud, and loss of customer trust. The hospitality industry in Europe is a lucrative target due to the volume of personal and payment data processed. Additionally, compromised systems could be used as a foothold for further attacks within an organization's network. The impact extends beyond individual hotels to booking platforms and third-party service providers integrated with HotelDruid. Given the widespread use of this software in countries with large tourism sectors, the potential scale of impact is considerable.

1. Immediate mitigation should focus on applying official patches or updates from HotelDruid once they become available. 2. Until patches are released, implement strict input validation and output encoding on the /modifica_app.php endpoint to neutralize malicious scripts. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 4. Conduct thorough code reviews and security testing of the affected application components to identify and remediate similar vulnerabilities. 5. Educate staff and users about the risks of clicking on suspicious links or interacting with untrusted content. 6. Monitor web server logs and application behavior for signs of attempted exploitation or unusual activity. 7. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block XSS attack patterns targeting HotelDruid. 8. Regularly back up application data and ensure incident response plans are in place to quickly address any breach.