CVE-2025-54300 is a high-severity stored Cross-Site Scripting (XSS) vulnerability identified in the Quantum Manager component versions 1.0.0 through 3.2.0 for Joomla, developed by norrnext.com. The vulnerability arises due to improper sanitization of SVG file uploads within the component's SVG upload feature. Specifically, malicious actors can upload crafted SVG files containing embedded scripts that are not neutralized during web page generation. When these SVG files are rendered by the Joomla site, the embedded scripts execute in the context of the victim's browser, enabling attackers to perform unauthorized actions such as session hijacking, defacement, or delivering further malware. The vulnerability is classified under CWE-79, indicating improper input neutralization during web page generation. The CVSS v4.0 score of 8.5 reflects its high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no user interaction (UI:N), and no privileges required (PR:H) but with high impact on confidentiality, integrity, and availability (VC:H, SI:H, SA:H). Although no known exploits are currently reported in the wild, the vulnerability's nature and ease of exploitation make it a significant risk for affected Joomla sites using this component. The lack of available patches at the time of publication further elevates the urgency for mitigation.

For European organizations, this vulnerability poses a substantial risk, especially for entities relying on Joomla-based websites that utilize the Quantum Manager component. Successful exploitation can lead to unauthorized access to sensitive user data, session hijacking, and potential defacement or disruption of web services. This can damage organizational reputation, lead to regulatory non-compliance under GDPR due to data breaches, and cause operational downtime. Given the widespread use of Joomla in Europe for government portals, educational institutions, and SMEs, the impact could be broad. Attackers exploiting this vulnerability could target high-profile organizations to gain footholds for further network intrusion or to conduct phishing campaigns leveraging compromised websites. The stored nature of the XSS means that malicious payloads persist on the server, increasing exposure duration and risk to multiple users.

Immediate mitigation steps include disabling the SVG upload feature in the Quantum Manager component until a secure patch is released. Organizations should implement strict input validation and sanitization on all file uploads, especially SVGs, using server-side filters that remove or neutralize embedded scripts. Employ Content Security Policy (CSP) headers to restrict script execution and reduce the impact of potential XSS payloads. Regularly audit and monitor web application logs for suspicious upload activity or anomalous behavior. Additionally, organizations should maintain up-to-date backups of their Joomla sites to enable quick restoration if compromised. Engage with the vendor or Joomla community to track patch releases and apply updates promptly once available. For enhanced security, consider deploying Web Application Firewalls (WAFs) configured to detect and block malicious SVG payloads and XSS attempts.