CVE-2025-54150: Qnap Qsync Central DoS Vulnerability

CVE-2025-54150 Overview

An uncontrolled resource consumption vulnerability has been identified in QNAP Qsync Central, a file synchronization application for QNAP NAS devices. This vulnerability allows a local attacker who has already obtained a valid user account to exploit the flaw and launch a denial-of-service (DoS) attack against the system. The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits or Throttling).

Critical Impact

Authenticated attackers can exhaust system resources, causing service unavailability and disrupting file synchronization operations for all users of the affected QNAP NAS device.

Affected Products

• QNAP Qsync Central versions prior to 5.0.0.4
• QNAP NAS devices running vulnerable Qsync Central installations
• Enterprise and home NAS deployments using Qsync Central for file synchronization

Discovery Timeline

• 2026-01-20 - QNAP releases security patch in Qsync Central version 5.0.0.4
• 2026-02-11 - CVE-2025-54150 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2025-54150

Vulnerability Analysis

This uncontrolled resource consumption vulnerability exists within QNAP Qsync Central's resource management mechanisms. The flaw stems from inadequate controls on resource allocation, allowing authenticated users to trigger excessive consumption of system resources such as CPU, memory, or disk I/O. When exploited, this can lead to degraded performance or complete unavailability of the Qsync Central service and potentially impact the overall NAS system stability.

The vulnerability requires an attacker to first obtain valid user credentials for the target system. Once authenticated, the attacker can submit requests or perform operations that consume disproportionate amounts of system resources, effectively denying service to legitimate users. This represents a post-authentication denial-of-service condition that could be particularly impactful in enterprise environments where file synchronization is critical to business operations.

Root Cause

The root cause of this vulnerability lies in the application's failure to implement proper resource allocation limits and throttling mechanisms. Specifically, CWE-770 (Allocation of Resources Without Limits or Throttling) indicates that the application does not adequately constrain the amount of resources that can be consumed by individual user requests or operations. This architectural weakness allows malicious authenticated users to monopolize system resources beyond reasonable operational requirements.

Attack Vector

The attack vector for CVE-2025-54150 is network-based, meaning an authenticated attacker can exploit this vulnerability remotely over the network connection to the QNAP NAS device. The attack requires low privileges (a valid user account) and no user interaction, making it relatively straightforward to execute once initial access is obtained.

An attacker would typically:

1. Obtain valid credentials for the Qsync Central application through credential theft, phishing, or by leveraging a compromised account
2. Authenticate to the Qsync Central service
3. Submit resource-intensive requests or perform operations designed to exhaust system resources
4. Continue the attack to maintain the denial-of-service condition

The impact is limited to availability (high availability impact), with no direct effect on confidentiality or integrity of data.

Detection Methods for CVE-2025-54150

Indicators of Compromise

• Unusual spikes in CPU or memory utilization on the QNAP NAS device correlating with Qsync Central activity
• Repeated or sustained high-volume requests from a single authenticated user account
• Service degradation or timeouts affecting Qsync Central file synchronization operations
• System logs showing resource exhaustion warnings or out-of-memory conditions

Detection Strategies

• Monitor system resource utilization metrics (CPU, memory, disk I/O) for anomalous patterns associated with Qsync Central processes
• Implement user activity logging and analysis to identify accounts generating excessive requests or operations
• Configure alerting thresholds for resource consumption that exceed normal operational baselines
• Review Qsync Central application logs for repeated error conditions or unusual activity patterns

Monitoring Recommendations

• Deploy endpoint detection and response (EDR) solutions to monitor process behavior and resource consumption on QNAP NAS devices
• Establish baseline resource utilization metrics for Qsync Central under normal operating conditions
• Configure SIEM rules to correlate authentication events with subsequent resource exhaustion indicators
• Implement periodic security assessments to verify patch levels and configuration hardening

How to Mitigate CVE-2025-54150

Immediate Actions Required

• Update QNAP Qsync Central to version 5.0.0.4 or later immediately
• Review user accounts with access to Qsync Central and disable any unnecessary or suspicious accounts
• Implement network segmentation to limit exposure of NAS management interfaces
• Enable comprehensive logging for Qsync Central to support forensic analysis if needed

Patch Information

QNAP has addressed this vulnerability in Qsync Central version 5.0.0.4, released on January 20, 2026. Administrators should update to this version or later to remediate the vulnerability. The security advisory with detailed patching instructions is available from the QNAP Security Advisory QSA-26-02.

To update Qsync Central:

1. Log into the QNAP NAS web interface
2. Navigate to App Center
3. Locate Qsync Central and check for available updates
4. Install version 5.0.0.4 or later

Workarounds

• Restrict network access to Qsync Central services to trusted IP addresses or network segments using firewall rules
• Implement rate limiting at the network level for connections to the NAS device
• Review and minimize user accounts with access to Qsync Central, applying the principle of least privilege
• Monitor system resource utilization closely and implement automated alerts for abnormal consumption patterns

# Example: Restrict Qsync Central access using iptables (on network firewall)
# Allow only trusted network segment to access NAS
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP

# Enable verbose logging for connection attempts
iptables -A INPUT -p tcp --dport 8080 -j LOG --log-prefix "QSYNC_ACCESS: "