CVE-2025-55288 is an authenticated reflected Cross-Site Scripting (XSS) vulnerability affecting the MGeurts genealogy PHP application versions prior to 4.4.0. The vulnerability arises from improper neutralization of user input during web page generation, classified under CWE-79. Authenticated attackers can exploit this flaw by injecting arbitrary JavaScript code that is reflected back in the response to another user's browser. This malicious script execution can lead to session hijacking, unauthorized data access, and manipulation of the user interface within the victim's session. Since the vulnerability requires authentication and user interaction (victim must visit a crafted link or page), the attack vector is somewhat limited but still significant in environments where multiple users have access to the genealogy application. The vulnerability has a CVSS 3.1 base score of 5.5 (medium severity), reflecting its moderate impact on confidentiality, integrity, and availability, with low attack complexity and requiring privileges and user interaction. The issue was addressed and fixed in version 4.4.0 of the application.

For European organizations using the MGeurts genealogy application, this vulnerability poses risks primarily to confidentiality and integrity of user sessions and data. Genealogy applications often store sensitive personal and familial information, which could be exposed or manipulated through this XSS flaw. In multi-user environments such as family history societies, research institutions, or community heritage projects prevalent in Europe, an attacker with valid credentials could exploit this vulnerability to hijack sessions of other users, steal personal data, or alter displayed information, undermining trust and data accuracy. Although the vulnerability does not allow unauthenticated remote exploitation, the potential for lateral movement within an organization or community platform exists. The impact on availability is limited but possible if UI manipulation disrupts normal application use. Given the moderate CVSS score and the nature of the application, the threat is significant for organizations relying on this software for sensitive genealogical data management.

To mitigate this vulnerability, organizations should upgrade the MGeurts genealogy application to version 4.4.0 or later, where the issue is fixed. Until the upgrade is applied, administrators should restrict access to trusted users only and monitor for suspicious activity indicative of XSS exploitation attempts. Implementing Content Security Policy (CSP) headers can help reduce the impact of XSS by restricting the execution of unauthorized scripts. Additionally, input validation and output encoding should be enforced at the application level to prevent injection of malicious scripts. Organizations should also educate users about the risks of clicking on untrusted links within the application context. Regular security audits and penetration testing focused on web application vulnerabilities can help detect similar issues proactively. Finally, logging and alerting on anomalous user behavior may help identify exploitation attempts early.