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 from improper neutralization of 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 not properly sanitized before being reflected in the web page output. Because the vulnerability is reflected, the malicious payload is delivered through a crafted URL or request parameter, which when visited or triggered by a victim, executes in the context of the victim's browser. The CVSS 4.0 base score is 5.1 (medium severity), reflecting that the attack vector is network-based (AV:N), requires no privileges (PR:N), but does require user interaction (UI:A). The impact on confidentiality and integrity is low, with no impact on availability. The vulnerability does not require authentication and affects all users who interact with the vulnerable component. No known exploits are currently reported in the wild. The vulnerability affects Joomla sites using the RSMail! component within the specified versions, which is a popular newsletter and email marketing extension. Exploitation could lead to session hijacking, phishing, or redirection attacks, potentially compromising user accounts or delivering malicious payloads to site visitors. Given Joomla's widespread use in Europe for various organizational websites, this vulnerability poses a tangible risk if left unpatched.

For European organizations using Joomla with the vulnerable RSMail! component, this XSS vulnerability could lead to targeted attacks against their web users, including customers, employees, or partners. Attackers could exploit the flaw to steal session cookies, perform unauthorized actions on behalf of users, or deliver malware through malicious scripts. This could result in reputational damage, loss of user trust, and potential regulatory consequences under GDPR if personal data is compromised. Organizations relying on Joomla for public-facing websites, especially those handling sensitive information or providing critical services, face increased risk. The reflected nature of the vulnerability means phishing campaigns could be crafted with URLs that appear legitimate but execute malicious scripts, increasing the likelihood of successful social engineering attacks. While the vulnerability does not directly impact system availability or integrity of backend data, the indirect effects through compromised user sessions or data leakage can be significant. Additionally, the lack of known exploits currently in the wild suggests a window of opportunity for proactive patching before widespread exploitation occurs.

European organizations should immediately verify if their Joomla installations use the RSMail! component versions 1.19.20 through 1.22.28. If so, they should upgrade to the latest patched version once available from rsjoomla.com or apply any official patches addressing CVE-2025-50056. In the interim, web application firewalls (WAFs) can be configured to detect and block suspicious input patterns indicative of XSS attacks targeting the vulnerable parameters. Input validation and output encoding should be enforced rigorously on all user-supplied data within the application. Organizations should also conduct security awareness training to educate users about the risks of clicking on suspicious links, reducing the effectiveness of phishing attempts leveraging this vulnerability. Regular security scanning and penetration testing focused on web application vulnerabilities can help detect residual or related issues. Monitoring web server logs for unusual request patterns targeting RSMail! parameters can provide early detection of exploitation attempts. Finally, implementing Content Security Policy (CSP) headers can mitigate the impact of XSS by restricting the execution of unauthorized scripts in browsers.