CVE-2025-44013: QNAP QuTS Hero DoS Vulnerability

CVE-2025-44013 Overview

CVE-2025-44013 is a NULL pointer dereference vulnerability [CWE-476] affecting multiple versions of QNAP QTS and QuTS hero operating systems. An authenticated remote attacker with a valid user account can trigger the flaw to cause a denial-of-service (DoS) condition on the affected network-attached storage (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 low privileges and no user interaction, but its impact is limited to availability.

Critical Impact

An authenticated remote attacker can crash affected QNAP NAS services, disrupting storage availability for legitimate users.

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)
• Multiple builds spanning QTS 5.2.0 through 5.2.6 and QuTS hero h5.2.0 through h5.3.0

Discovery Timeline

• 2026-01-02 - CVE CVE-2025-44013 published to NVD
• 2026-01-05 - Last updated in NVD database

Technical Details for CVE-2025-44013

Vulnerability Analysis

The vulnerability is a NULL pointer dereference [CWE-476] within QNAP's QTS and QuTS hero operating systems. NULL pointer dereferences occur when application code attempts to read from or write to a memory address held in a pointer that has not been initialized or has been set to NULL. On Linux-based platforms such as QNAP NAS firmware, dereferencing a NULL pointer typically results in a segmentation fault that terminates the affected process.

In this case, exploitation crashes a service component on the NAS, producing a denial-of-service condition. QNAP rates the issue as low severity because the attacker cannot read, modify, or escalate privileges through the flaw. The vulnerability only impacts availability, not confidentiality or integrity. The EPSS score is 0.203%, indicating a low likelihood of widespread exploitation activity.

Root Cause

The root cause is missing pointer validation in one or more code paths reachable by authenticated users. The affected code dereferences a pointer without first verifying that it references valid memory. When an attacker supplies input or invokes a function path that leaves the pointer uninitialized or NULL, the resulting dereference forces a process crash.

Attack Vector

Exploitation requires network access to the QNAP device and valid user credentials. An attacker who has obtained a low-privilege account, through credential theft, phishing, or weak password reuse, can send crafted requests that reach the vulnerable code path. No user interaction is needed once credentials are available. The attack does not require administrative privileges, making any compromised user account a viable foothold for a DoS attack.

No public exploit code or proof-of-concept has been published. There is no evidence of in-the-wild exploitation, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

No verified public exploit code is available. See the QNAP Security Advisory QSA-25-50 for vendor-supplied technical context.

Detection Methods for CVE-2025-44013

Indicators of Compromise

• Unexpected restarts or crashes of QTS or QuTS hero service processes recorded in system logs
• Repeated authenticated requests from a single source followed by service termination events
• Sudden loss of access to NAS shares or web management interface coinciding with user session activity

Detection Strategies

• Monitor QNAP system event logs for service crash entries and core dumps associated with authenticated sessions
• Correlate authentication events with subsequent service failures to identify accounts triggering crashes
• Track failed and successful logins from unusual source IP addresses against NAS administrative interfaces

Monitoring Recommendations

• Forward QNAP syslog output to a centralized logging platform for correlation and retention
• Alert on repeated process restarts of NAS daemons within short time windows
• Review user account activity for low-privilege accounts performing administrative-style requests

How to Mitigate CVE-2025-44013

Immediate Actions Required

• Update QTS to version 5.2.6.3195 build 20250715 or later
• Update QuTS hero to version h5.2.6.3195 build 20250715 or later
• Audit all user accounts on affected NAS devices and disable unused or stale accounts
• Enforce strong, unique passwords and enable two-factor authentication for all NAS users

Patch Information

QNAP has released fixed firmware in QTS 5.2.6.3195 build 20250715 and QuTS hero h5.2.6.3195 build 20250715. Apply these updates through the QNAP App Center or the Control Panel firmware update utility. Refer to QNAP Security Advisory QSA-25-50 for full patching guidance.

Workarounds

• Restrict NAS management interface exposure to trusted internal networks using firewall rules
• Place the NAS behind a VPN to remove direct internet exposure of authenticated endpoints
• Limit the number of user accounts with remote access until patching is complete
• Enable QNAP's built-in access protection to throttle repeated requests from a single source

# Configuration example
# Verify installed firmware version on QNAP device via SSH
getcfg System Version -f /etc/config/uLinux.conf
getcfg System "Build Number" -f /etc/config/uLinux.conf

# Restrict management access by source IP using QNAP Access Protection
# Control Panel > System > Security > Allow/Deny List