CVE-2025-62802 is a vulnerability identified in the Dnn.Platform, an open-source web content management system widely used in the Microsoft ecosystem. The root cause is an insecure default initialization of the HTML editor component prior to version 10.1.1, which permits unauthenticated users to upload files. This behavior violates secure default principles and introduces a significant attack surface. The vulnerability is classified under CWE-1188 (Insecure Default Initialization of Resource) and CWE-434 (Unrestricted Upload of File with Dangerous Type). Although the vulnerability itself does not directly disclose sensitive information or cause denial of service, it enables attackers to upload potentially malicious files, such as web shells or scripts, which can be leveraged for further attacks including privilege escalation, data tampering, or persistent access. The CVSS v3.1 score is 4.3 (medium), reflecting the network attack vector, no privileges required, but requiring user interaction (e.g., triggering the upload functionality). No known exploits are currently reported in the wild, but the risk remains significant due to the ease of exploitation and the common use of Dnn.Platform in enterprise web environments. The vulnerability is resolved in version 10.1.1 by disabling or securing the default file upload functionality for unauthenticated users.

For European organizations, this vulnerability poses a moderate risk primarily to web integrity and security posture. Organizations running vulnerable versions of Dnn.Platform may face unauthorized file uploads that could lead to website defacement, injection of malicious scripts, or establishment of backdoors. This can result in reputational damage, regulatory scrutiny under GDPR if personal data is compromised, and potential lateral movement within internal networks. The impact is more pronounced for public-facing websites or portals that rely on Dnn.Platform for content management. Since the vulnerability does not directly affect confidentiality or availability, the immediate operational disruption may be limited, but the indirect consequences of a successful attack could be severe. Organizations in sectors with high web presence, such as government, education, and media, are particularly at risk.

European organizations should immediately upgrade all Dnn.Platform instances to version 10.1.1 or later to remediate this vulnerability. Until upgrades can be applied, administrators should disable or restrict the HTML editor's file upload functionality for unauthenticated users through configuration changes or access controls. Implement web application firewalls (WAFs) with rules to detect and block unauthorized file upload attempts targeting Dnn.Platform endpoints. Conduct thorough audits of existing uploaded files to identify and remove any unauthorized or suspicious content. Additionally, enforce strict input validation and file type restrictions on uploads, and monitor logs for unusual upload activity. Regularly review user permissions and ensure that only authenticated and authorized users have file upload capabilities. Finally, maintain an incident response plan to quickly address any exploitation attempts.