CVE-2025-52865 is a NULL pointer dereference vulnerability identified in QNAP Systems Inc.'s File Station 5 product, specifically affecting versions 5.5.x. This vulnerability is classified under CWE-476, which involves dereferencing a NULL pointer leading to application crashes or denial-of-service conditions. The flaw allows a remote attacker who has already obtained a valid user account on the system to trigger a denial-of-service attack by exploiting the NULL pointer dereference, causing the File Station service to crash or become unresponsive. The vulnerability does not require any user interaction beyond possessing valid credentials, and it does not affect confidentiality or integrity of data, only availability. The CVSS v4.0 base score is 1.3, reflecting low severity due to the need for authentication and limited impact. The vendor has addressed this issue in File Station 5 version 5.5.6.5018 and later, and no public exploits have been reported so far. The vulnerability's exploitation vector is network-based with low attack complexity and no privileges beyond user-level access. This vulnerability highlights the importance of timely patching and restricting user account creation or access to trusted personnel to minimize risk.

For European organizations, the primary impact of CVE-2025-52865 is a potential denial-of-service condition on QNAP File Station 5 services, which could disrupt file management operations and availability of shared resources. Organizations relying heavily on QNAP NAS devices for file storage and sharing may experience temporary service outages, affecting business continuity and productivity. Since the vulnerability requires authenticated access, the risk is mitigated if strong access controls and user account management policies are enforced. However, in environments where user accounts are widely distributed or less strictly controlled, the risk of exploitation increases. The vulnerability does not compromise data confidentiality or integrity, so the impact is limited to availability. European sectors with critical reliance on QNAP NAS devices, such as SMBs, educational institutions, and public sector organizations, could face operational disruptions if the vulnerability is exploited. The absence of known exploits reduces immediate risk but does not eliminate the need for proactive mitigation.

European organizations should immediately upgrade QNAP File Station 5 to version 5.5.6.5018 or later to remediate this vulnerability. Until patching is complete, organizations should enforce strict user account management policies, limiting the number of users with access to File Station and regularly reviewing account permissions. Implement network segmentation to restrict access to QNAP NAS devices only to trusted internal networks and users. Monitor logs for unusual activity or repeated service crashes that could indicate attempted exploitation. Employ multi-factor authentication (MFA) where possible to reduce the risk of unauthorized account access. Regularly back up critical data stored on QNAP devices to minimize impact from potential service disruptions. Additionally, disable or restrict File Station services if not required to reduce the attack surface. Maintain awareness of vendor advisories for any updates or additional patches.