CVE-2025-40652 is a stored Cross-Site Scripting (XSS) vulnerability affecting all versions of the CoverManager booking software. This vulnerability arises from improper neutralization of input during web page generation (CWE-79), allowing an attacker to inject malicious scripts that are permanently stored on the server. When users access the affected pages, these scripts execute in their browsers without requiring any further interaction, such as clicking a link or submitting a form. The exploitation of this vulnerability can lead to theft of sensitive information including session cookies and login credentials, enabling attackers to hijack user sessions or perform unauthorized actions on behalf of the victim. The vulnerability has a CVSS 4.0 base score of 5.3, indicating a medium severity level. The attack vector is network-based with low attack complexity and no privileges or user interaction required, but the vulnerability does require the victim to visit the compromised page. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability affects all versions of CoverManager, a booking software widely used in hospitality and event management sectors, which often handle sensitive customer and booking data. The improper input sanitization likely stems from insufficient filtering or encoding of user-supplied data before rendering it in web pages, a common cause of stored XSS vulnerabilities. This type of vulnerability is particularly dangerous because the malicious payload persists on the server and can affect multiple users over time, increasing the attack surface and potential impact.

For European organizations using CoverManager, this vulnerability poses a significant risk to confidentiality and integrity of user data. Attackers exploiting this flaw can steal session tokens and credentials, potentially leading to unauthorized access to booking systems and customer information. This can result in data breaches, financial fraud, and reputational damage. Additionally, attackers could perform actions on behalf of legitimate users, such as modifying bookings or accessing sensitive internal functions, disrupting business operations. Given the hospitality and event sectors' importance in Europe, especially in countries with large tourism industries, the impact could extend to customer trust and regulatory compliance under GDPR. The persistent nature of stored XSS means that multiple users can be affected over time, increasing the likelihood of widespread compromise. Although the vulnerability does not directly affect system availability, the indirect consequences of unauthorized access and data leakage can be severe. The lack of available patches increases the urgency for organizations to implement compensating controls until a fix is released.

European organizations should immediately implement input validation and output encoding controls on all user-supplied data within CoverManager, especially in fields that are rendered on web pages. Employing a web application firewall (WAF) with rules specifically targeting XSS payloads can provide a temporary protective layer. Organizations should conduct thorough code reviews and penetration testing focused on input sanitization to identify and remediate similar issues. Until an official patch is released, restricting access to the affected application to trusted networks or VPNs can reduce exposure. User education to recognize suspicious behavior and monitoring logs for unusual activity related to session hijacking attempts are also recommended. Additionally, implementing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting the execution of unauthorized scripts. Regular backups and incident response plans should be updated to handle potential exploitation scenarios. Finally, organizations should maintain close communication with CoverManager vendors for timely patch releases and updates.