CVE-2025-50056 is a reflected Cross-Site Scripting (XSS) vulnerability identified in the RSMail! component versions 1.19.20 through 1.22.28 for the Joomla content management system. This vulnerability arises due to improper neutralization of user-supplied input during web page generation, classified under CWE-79. Specifically, the flaw allows remote attackers to inject arbitrary web scripts or HTML code via crafted parameters that are reflected back in the web application's response without adequate sanitization or encoding. Exploitation does not require authentication, and no privileges are needed, making it accessible to unauthenticated attackers. The vulnerability has a CVSS 4.0 base score of 5.1, indicating medium severity, with attack vector being network-based, low attack complexity, no privileges required, but user interaction is necessary for successful exploitation. The impact on confidentiality and integrity is low, with limited impact on availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability affects a widely used Joomla extension, RSMail!, which is popular for managing email campaigns and newsletters within Joomla-based websites. Given the nature of reflected XSS, successful exploitation could lead to session hijacking, phishing, or redirection to malicious sites, potentially compromising user data and trust in affected websites.

For European organizations, especially those relying on Joomla-based websites with the RSMail! component installed, this vulnerability poses a risk of client-side attacks that can compromise end-user security. Attackers could exploit this flaw to execute malicious scripts in the browsers of site visitors, leading to theft of session cookies, credentials, or delivery of malware. This can damage organizational reputation, lead to data breaches involving personal data protected under GDPR, and cause regulatory and financial repercussions. Organizations in sectors with high web presence such as e-commerce, government portals, education, and media are particularly at risk. The reflected XSS could also be leveraged in targeted phishing campaigns against European users, increasing the threat landscape. Although the vulnerability does not directly compromise server integrity or availability, the indirect consequences through user compromise and trust erosion can be significant.

European organizations should prioritize updating the RSMail! component to a version beyond 1.22.28 once patches are released by rsjoomla.com. Until official patches are available, implementing Web Application Firewall (WAF) rules to detect and block suspicious input patterns targeting the vulnerable parameters can reduce risk. Input validation and output encoding should be enforced at the application level, ensuring all user-supplied data is properly sanitized before rendering. Organizations should conduct thorough security testing of their Joomla installations, including penetration testing focused on XSS vectors. Additionally, educating users about the risks of clicking on suspicious links and employing Content Security Policy (CSP) headers can mitigate the impact of potential XSS payloads. Monitoring web logs for unusual request patterns and anomalous user behavior can help detect exploitation attempts early. Finally, maintaining regular backups and incident response plans tailored to web application attacks will improve resilience.