CVE-2025-52858 Overview
CVE-2025-52858 is a NULL pointer dereference vulnerability [CWE-476] affecting QNAP QTS and QuTS hero operating systems. An authenticated remote attacker with administrator privileges can trigger the flaw to cause a denial-of-service (DoS) condition on the affected NAS device. QNAP addressed the issue in QTS 5.2.6.3195 build 20250715 and QuTS hero h5.2.6.3195 build 20250715. The vulnerability requires high privileges to exploit and does not permit code execution or data disclosure.
Critical Impact
An authenticated attacker holding an administrator account can crash the affected QNAP NAS process, disrupting storage and services until recovery.
Affected Products
- QNAP QTS versions prior to 5.2.6.3195 build 20250715
- QNAP QuTS hero versions prior to h5.2.6.3195 build 20250715
- QNAP NAS appliances running the impacted operating system builds listed in advisory QSA-25-36
Discovery Timeline
- 2025-10-03 - CVE-2025-52858 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-52858
Vulnerability Analysis
The vulnerability is a NULL pointer dereference [CWE-476] in QNAP QTS and QuTS hero. The affected code path dereferences a pointer without first validating that it references a valid memory object. When an authenticated administrator submits input that reaches this code path, the process attempts to read or write through the NULL pointer and crashes. The impact is limited to availability. Confidentiality and integrity are unaffected according to the CVSS vector. Because exploitation requires administrator credentials, the practical attack surface is confined to scenarios where administrator accounts are compromised, shared, or abused by insiders.
Root Cause
The root cause is missing input or state validation before a pointer dereference in a QTS or QuTS hero service accessible to authenticated administrators. QNAP has not published function-level details in advisory QSA-25-36. The fix in build 20250715 introduces additional checks to ensure the affected object is initialized before dereference.
Attack Vector
The attack vector is network-based. A remote attacker who has already obtained an administrator account authenticates to the QNAP management interface and sends crafted input to the vulnerable component. The malformed request causes the target process to dereference a NULL pointer and terminate, resulting in a denial-of-service condition against the impacted service.
No public proof-of-concept is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the QNAP Security Advisory QSA-25-36 for vendor guidance.
Detection Methods for CVE-2025-52858
Indicators of Compromise
- Unexpected termination or repeated restarts of QTS or QuTS hero service processes on the NAS appliance.
- Administrator-authenticated web or API requests immediately preceding a service crash or unavailability event.
- System logs showing segmentation faults or core dumps tied to management daemons on unpatched builds.
Detection Strategies
- Correlate administrator authentication events with subsequent service failures within short time windows.
- Alert on abnormal sequences of administrator API calls that deviate from routine management activity.
- Track version and build strings across the NAS fleet to identify appliances running QTS or QuTS hero builds earlier than 20250715.
Monitoring Recommendations
- Forward QNAP system, event, and access logs to a centralized logging platform for retention and analysis.
- Monitor administrative logon sources and flag interactive administrator sessions originating from unexpected networks or geographies.
- Alert when NAS management services restart outside scheduled maintenance windows.
How to Mitigate CVE-2025-52858
Immediate Actions Required
- Upgrade affected devices to QTS 5.2.6.3195 build 20250715 or later, or QuTS hero h5.2.6.3195 build 20250715 or later.
- Audit all administrator accounts on QNAP appliances and remove or disable unused or shared credentials.
- Enforce multi-factor authentication for every administrator account on the NAS management interface.
- Restrict management interface exposure to trusted internal networks and VPN-only access paths.
Patch Information
QNAP resolved the vulnerability in QTS 5.2.6.3195 build 20250715 and QuTS hero h5.2.6.3195 build 20250715. Administrators should apply the update through the QTS or QuTS hero Live Update mechanism or download the firmware directly from QNAP. Full remediation details are documented in QNAP Security Advisory QSA-25-36.
Workarounds
- Limit administrator interface exposure with firewall rules that permit access only from designated management subnets.
- Enforce strong, unique passwords and rotate credentials for any administrator account with access to the NAS management console.
- Disable direct internet exposure of the QNAP web administration portal until the patch is applied.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
