CVE-2025-57710: Qnap Qsync Central DOS Vulnerability

CVE-2025-57710 Overview

An allocation of resources without limits or throttling vulnerability (CWE-770) has been identified in QNAP Qsync Central. This vulnerability allows a remote attacker who has compromised an administrator account to exploit the flaw and prevent other systems, applications, or processes from accessing the same type of resource, effectively causing a denial of service condition.

Critical Impact

Authenticated attackers with administrator privileges can exhaust system resources, disrupting synchronization services and potentially affecting dependent systems connected to the QNAP NAS device.

Affected Products

• QNAP Qsync Central versions prior to 5.0.0.4

Discovery Timeline

• 2026-01-20 - QNAP releases security patch in Qsync Central version 5.0.0.4
• 2026-02-11 - CVE-2025-57710 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2025-57710

Vulnerability Analysis

This vulnerability falls under the Resource Exhaustion category (CWE-770: Allocation of Resources Without Limits or Throttling). The flaw exists in Qsync Central's resource management mechanisms, where the application fails to properly limit or throttle resource allocation requests. When exploited by an attacker with administrator-level access, this can lead to the exhaustion of system resources, preventing legitimate users and processes from accessing necessary resources for normal operation.

The attack requires network access and high privileges (administrator account), combined with specific conditions that must be present for successful exploitation. The primary impact is on availability, affecting both the vulnerable system and potentially downstream systems that depend on the synchronization service.

Root Cause

The root cause stems from improper resource allocation controls within Qsync Central. The application does not implement adequate limits or throttling mechanisms for resource consumption, allowing authenticated administrators to request resources beyond what the system can sustainably provide. This design flaw enables resource exhaustion attacks when malicious or compromised administrator credentials are used.

Attack Vector

The attack vector is network-based, requiring the attacker to first obtain valid administrator credentials for the Qsync Central application. Once authenticated with elevated privileges, the attacker can initiate resource-intensive operations that consume system resources without proper throttling, leading to denial of service conditions affecting the synchronization infrastructure and connected systems.

The exploitation scenario involves:

1. Attacker gains access to administrator credentials through credential theft, social engineering, or brute force attacks
2. Attacker authenticates to Qsync Central with administrator privileges
3. Attacker initiates resource allocation requests that bypass throttling controls
4. System resources become exhausted, preventing legitimate access to synchronization services

Detection Methods for CVE-2025-57710

Indicators of Compromise

• Unusual resource consumption patterns on QNAP NAS devices running Qsync Central
• Multiple failed or disrupted synchronization operations for legitimate users
• Abnormal administrator login patterns or login attempts from unexpected locations
• System performance degradation coinciding with administrator activity

Detection Strategies

• Monitor Qsync Central logs for anomalous administrator activity patterns
• Implement resource utilization baselines and alert on significant deviations
• Deploy network monitoring to detect unusual traffic volumes to Qsync Central endpoints
• Review administrator account activity for signs of compromise or misuse

Monitoring Recommendations

• Enable comprehensive logging for all administrator actions within Qsync Central
• Configure alerts for resource utilization thresholds on QNAP devices
• Implement network-level monitoring for connections to Qsync Central services
• Regularly audit administrator account access and review login history

How to Mitigate CVE-2025-57710

Immediate Actions Required

• Update Qsync Central to version 5.0.0.4 or later immediately
• Audit all administrator accounts for signs of compromise
• Implement strong authentication controls including multi-factor authentication where supported
• Review and restrict administrator account access to essential personnel only

Patch Information

QNAP has addressed this vulnerability in Qsync Central version 5.0.0.4, released on January 20, 2026. Organizations should apply this update as soon as possible. For detailed patch information and download instructions, refer to the QNAP Security Advisory QSA-26-02.

Workarounds

• Restrict network access to Qsync Central administrative interfaces using firewall rules
• Limit administrator account privileges to the minimum required for operational needs
• Implement network segmentation to isolate QNAP NAS devices from untrusted networks
• Enable and monitor administrator activity logging to detect potential abuse

# Network access restriction example for QNAP devices
# Restrict administrative access to trusted management network only
# Configure these rules on your network firewall or QNAP security settings

# Example iptables rule to limit access to management interface
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP