CVE-2025-48377 is a cross-site scripting (XSS) vulnerability identified in the Dnn.Platform, an open-source web content management system widely used within the Microsoft ecosystem. The vulnerability exists in versions prior to 9.13.9 and arises due to improper neutralization of input during web page generation, specifically when processing certain module actions triggered via specially crafted URLs. An attacker can exploit this flaw by constructing a malicious URL that injects executable script code into the web application. When a user interacts with the affected module or page, the injected script executes in the context of the victim's browser, potentially allowing the attacker to steal session tokens, manipulate web content, or perform actions on behalf of the user. The vulnerability is classified under CWE-79, indicating a failure to properly sanitize or encode user-supplied input before rendering it in a web page. The CVSS 4.0 base score is 6.0 (medium severity), reflecting that the attack vector is network-based, requires no privileges, but does require user interaction to trigger the payload. The vulnerability does not impact confidentiality, integrity, or availability directly but can lead to session hijacking or unauthorized actions if exploited. No known exploits are currently reported in the wild, and the issue was addressed in version 9.13.9 of the Dnn.Platform. The vulnerability is particularly relevant for organizations using Dnn as their CMS, especially those exposing module actions via URLs to external users.

For European organizations using Dnn.Platform versions prior to 9.13.9, this vulnerability poses a risk of client-side attacks that can compromise user sessions and lead to unauthorized actions within the CMS environment. This can result in unauthorized content modification, defacement, or data leakage through session hijacking. While the vulnerability does not directly compromise server-side data confidentiality or availability, successful exploitation can undermine user trust and lead to reputational damage. Organizations in sectors with high regulatory scrutiny, such as finance, healthcare, and government, may face compliance risks if user data is compromised. Additionally, attackers could leverage this vulnerability as a foothold to conduct further attacks within the network, especially if administrative users are targeted. The requirement for user interaction somewhat limits the attack scope, but phishing or social engineering campaigns could increase exploitation likelihood. Given the widespread use of Dnn in European public sector and enterprise environments, the impact can be significant if unpatched.

1. Immediate upgrade to Dnn.Platform version 9.13.9 or later to apply the official patch addressing the XSS vulnerability. 2. Implement strict Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS payloads. 3. Conduct a thorough audit of all custom modules and third-party extensions to ensure they properly sanitize and encode user inputs, especially those handling URL parameters or module actions. 4. Employ web application firewalls (WAFs) with rules tuned to detect and block suspicious URL patterns indicative of XSS attempts targeting Dnn modules. 5. Educate users and administrators about phishing risks and the importance of avoiding clicking on suspicious links, as user interaction is required for exploitation. 6. Monitor web server and application logs for unusual URL requests or error patterns that may indicate attempted exploitation. 7. For organizations unable to immediately patch, consider temporarily restricting access to vulnerable modules or implementing URL filtering to block malicious payloads.