CVE-2025-67558 is a stored cross-site scripting (XSS) vulnerability identified in the Jacques Malgrange Rencontre web application, specifically affecting versions up to and including 3.13.7. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, which allows malicious scripts to be stored on the server and subsequently executed in the browsers of users who view the affected pages. Stored XSS is particularly dangerous because the malicious payload persists on the server and can affect multiple users without requiring repeated attacker interaction. Attackers can exploit this vulnerability by submitting crafted input that includes malicious JavaScript code, which is then stored and rendered by the application. This can lead to session hijacking, theft of cookies or credentials, unauthorized actions performed on behalf of users, or defacement of the website. The vulnerability does not require authentication, increasing its risk profile, and no user interaction beyond visiting the compromised page is necessary for exploitation. Although no public exploits have been reported yet, the vulnerability is published and should be considered a significant threat. The lack of a CVSS score indicates that the severity assessment must be based on the nature of the vulnerability, its impact on confidentiality, integrity, and availability, and the ease of exploitation. The affected product, Rencontre, is a web-based platform, likely used for social or dating interactions, which increases the risk of sensitive personal data exposure. The absence of official patches or mitigation links in the provided data suggests that organizations must proactively implement security best practices to reduce risk.

For European organizations, the impact of CVE-2025-67558 can be substantial, particularly for those operating or hosting the Rencontre platform or similar web applications. Stored XSS vulnerabilities can lead to the compromise of user accounts through session hijacking, theft of sensitive personal information, and unauthorized actions performed on behalf of users, which can damage user trust and lead to regulatory penalties under GDPR. The reputational damage from defacement or data breaches can be significant, especially for platforms handling personal or dating information. Additionally, attackers could use the vulnerability as a foothold to escalate attacks within the network or distribute malware. The ease of exploitation without authentication increases the risk of widespread attacks. European organizations with large user bases or those in countries with high adoption of Rencontre are particularly vulnerable. The potential for data leakage and service disruption also raises concerns about compliance with European data protection laws and the need for timely incident response.

Organizations should immediately review their use of the Rencontre platform and apply any available updates or patches once released. In the absence of official patches, implement strict input validation on all user-supplied data to ensure that scripts or HTML tags are sanitized before storage. Employ robust output encoding techniques to neutralize any potentially malicious content before rendering it in web pages. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. Conduct regular security audits and penetration testing focused on input handling and web application security. Educate developers on secure coding practices to prevent similar vulnerabilities in future releases. Additionally, monitor web application logs for suspicious input patterns or unusual user activity that may indicate exploitation attempts. Consider isolating the Rencontre application environment to limit potential lateral movement in case of compromise. Finally, prepare incident response plans that include steps for containment, eradication, and recovery from XSS-related incidents.