CVE-2025-44011 Overview
CVE-2025-44011 is a NULL pointer dereference vulnerability [CWE-476] in QNAP Qsync Central. An authenticated remote attacker can exploit the flaw to trigger a denial-of-service (DoS) condition on affected deployments. QNAP addressed the issue in Qsync Central version 5.0.0.1 released on July 9, 2025. The vulnerability requires low privileges and no user interaction, making it accessible to any attacker with valid credentials on the target system.
Critical Impact
An authenticated remote attacker can crash the Qsync Central service, disrupting file synchronization across connected QNAP NAS devices and endpoints.
Affected Products
- QNAP Qsync Central versions prior to 5.0.0.1
- QNAP NAS devices running vulnerable Qsync Central builds
- Deployments synchronizing files across endpoints via Qsync Central
Discovery Timeline
- 2025/07/09 - QNAP releases Qsync Central 5.0.0.1 with the fix
- 2025-10-03 - CVE-2025-44011 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-44011
Vulnerability Analysis
The flaw is a NULL pointer dereference in Qsync Central, QNAP's centralized file synchronization service for NAS environments. When the vulnerable code path receives attacker-controlled input, it dereferences a pointer that was never initialized or has been set to NULL. This triggers a segmentation fault that terminates the affected process.
The attack requires a valid user account on the target device. Once authenticated, the attacker can send crafted requests to the service to trigger the fault. Successful exploitation disrupts synchronization across all devices connected to the Qsync Central instance. Confidentiality and integrity are not affected, but availability of the synchronization service is lost until the process is restarted.
Root Cause
The root cause is improper validation of a pointer prior to dereference, classified as [CWE-476] NULL Pointer Dereference. QNAP has not published the specific code path or request pattern that triggers the condition. See the QNAP Security Advisory QSA-25-34 for vendor-confirmed details.
Attack Vector
The attack vector is network-based with low attack complexity. An attacker requires a valid user account to reach the vulnerable code path. No user interaction is needed. The impact is limited to loss of availability for the Qsync Central service. Technical exploitation details are not available in public references, and no public proof-of-concept has been published.
Detection Methods for CVE-2025-44011
Indicators of Compromise
- Unexpected crashes or restarts of the Qsync Central process on QNAP NAS devices
- Interruption of file synchronization sessions across connected clients
- Authenticated session activity from unusual source IPs preceding service failure
Detection Strategies
- Query the Qsync Central version on all QNAP appliances and flag any build earlier than 5.0.0.1
- Correlate authenticated API or synchronization requests with subsequent service termination events
- Review NAS system logs for segmentation faults or abnormal exits of the Qsync Central daemon
Monitoring Recommendations
- Forward QNAP NAS system and application logs to a centralized logging platform for correlation
- Alert on repeated authentication from a single account followed by Qsync Central restarts
- Track service uptime for Qsync Central and alert on unexpected restarts
How to Mitigate CVE-2025-44011
Immediate Actions Required
- Upgrade Qsync Central to version 5.0.0.1 or later on all QNAP devices
- Audit Qsync Central user accounts and remove inactive or unnecessary credentials
- Restrict network reachability of Qsync Central to trusted management networks
Patch Information
QNAP fixed the vulnerability in Qsync Central 5.0.0.1, released on 2025/07/09. Administrators should install the update through the App Center on affected NAS devices. Refer to QNAP Security Advisory QSA-25-34 for official vendor guidance.
Workarounds
- Enforce strong password policies and multi-factor authentication for all Qsync Central accounts
- Place QNAP NAS management interfaces behind a VPN or firewall to limit exposure
- Disable Qsync Central on devices where the service is not required until patching is complete
# Verify installed Qsync Central version on a QNAP NAS
qpkg_cli --list | grep -i qsync
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
