CVE-2025-54164 is classified as a CWE-125 out-of-bounds read vulnerability affecting QNAP Systems Inc.'s QTS operating system, specifically versions 5.2.x. This vulnerability allows a remote attacker who has already obtained administrator-level access to perform an out-of-bounds read operation, enabling them to access sensitive or secret data stored in memory regions outside the intended boundaries. The flaw arises from insufficient bounds checking in the affected QTS versions, which can be exploited without requiring user interaction but does require elevated privileges (administrator). The vulnerability impacts confidentiality but does not affect integrity or availability directly. The CVSS v4.0 score is 4.6 (medium severity), reflecting the need for administrator privileges and the limited scope of impact. QNAP has addressed this vulnerability in QTS 5.2.7.3256 build 20250913 and later, as well as in QuTS hero h5.2.7.3256 and h5.3.1.3250 builds released in September 2025. No public exploits have been reported to date, but the vulnerability poses a risk if attackers gain admin credentials through other means. Given QNAP's widespread use in enterprise and SMB environments for network-attached storage, this vulnerability could lead to unauthorized disclosure of sensitive information if left unpatched.

For European organizations, the primary impact of CVE-2025-54164 is the potential unauthorized disclosure of sensitive data stored on QNAP NAS devices. Since exploitation requires administrator privileges, the threat is heightened in environments where credential compromise or insider threats exist. Confidentiality breaches could affect intellectual property, customer data, or internal communications, leading to regulatory compliance issues under GDPR and reputational damage. The vulnerability does not directly impact system availability or integrity, but data leakage risks could facilitate further attacks or espionage. Organizations relying heavily on QNAP NAS for critical data storage, especially in sectors like finance, healthcare, and government, face increased risk. The absence of known exploits reduces immediate threat but does not eliminate the risk, particularly as attackers may develop exploits targeting this vulnerability. Patch deployment delays could exacerbate exposure, especially in large or distributed environments.

European organizations should immediately verify their QNAP NAS firmware versions and upgrade to the patched releases: QTS 5.2.7.3256 build 20250913 or later, and QuTS hero h5.2.7.3256 or h5.3.1.3250 builds or later. Restrict administrator access to trusted personnel and enforce strong authentication mechanisms, such as multi-factor authentication, to reduce the risk of credential compromise. Regularly audit administrator account activity and monitor for unusual access patterns. Employ network segmentation to isolate NAS devices from less secure network zones and limit exposure to external networks. Implement strict access controls and logging on NAS devices to detect potential exploitation attempts. Additionally, conduct vulnerability scanning and penetration testing focused on NAS devices to identify any residual risks. Educate IT staff about the importance of timely patching and monitoring for this specific vulnerability. Finally, maintain up-to-date backups to mitigate potential data loss from other attack vectors.