CVE-2025-48378 is a medium severity cross-site scripting (XSS) vulnerability identified in the Dnn.Platform, an open-source web content management system widely used in the Microsoft ecosystem. The vulnerability affects all versions prior to 9.13.9. The root cause lies in the improper neutralization of input during web page generation, specifically related to the handling of uploaded SVG (Scalable Vector Graphics) files. SVG files can contain embedded scripts, and if these files are rendered inline without proper sanitization, malicious scripts can execute in the context of the victim's browser. This allows an attacker to perform XSS attacks, potentially stealing session tokens, performing actions on behalf of authenticated users, or delivering further malicious payloads. The vulnerability does not require authentication but does require user interaction (such as viewing a page with the malicious SVG). The CVSS 4.0 base score is 6.1, reflecting a network attack vector, low attack complexity, no privileges required, but user interaction needed. The vulnerability has not been reported exploited in the wild yet. The fix was introduced in version 9.13.9, which presumably includes proper sanitization or disallows inline script execution in SVG uploads. This vulnerability is categorized under CWE-79, indicating improper neutralization of input leading to XSS.

For European organizations using Dnn.Platform versions prior to 9.13.9, this vulnerability poses a significant risk to the confidentiality and integrity of web applications. Successful exploitation could lead to session hijacking, unauthorized actions, or data theft from users interacting with affected web portals. This is particularly critical for organizations hosting customer portals, intranets, or public-facing websites where SVG uploads are allowed or user-generated content is displayed. The impact is heightened in sectors with sensitive data such as finance, healthcare, and government services. Additionally, compromised websites could be used to distribute malware or conduct phishing campaigns, further amplifying the threat. Given the medium severity and the requirement for user interaction, the threat is moderate but should not be underestimated, especially in environments with high user traffic or valuable data. The lack of known exploits in the wild provides a window for proactive mitigation.

European organizations should immediately verify their Dnn.Platform version and upgrade to version 9.13.9 or later to remediate this vulnerability. If immediate upgrade is not feasible, organizations should implement strict input validation and sanitization on SVG uploads, disallow inline script execution within SVG files, or restrict SVG uploads altogether. Web application firewalls (WAFs) can be configured to detect and block malicious SVG payloads containing scripts. Additionally, organizations should audit their content management policies to limit who can upload SVG files and monitor logs for suspicious upload activity. User education about the risks of interacting with untrusted content can reduce the likelihood of exploitation. Regular vulnerability scanning and penetration testing focused on XSS vectors in the CMS environment are recommended to detect residual or related issues.