CVE-2025-58471: Qnap Qsync Central DoS Vulnerability

CVE-2025-58471 Overview

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

Critical Impact

Authenticated administrators can exhaust system resources, preventing legitimate access to shared resources and disrupting synchronization services for other users and processes.

Affected Products

• QNAP Qsync Central versions prior to 5.2.0.1

Discovery Timeline

• 2026-02-11 - CVE-2025-58471 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2025-58471

Vulnerability Analysis

This vulnerability stems from improper resource allocation controls within QNAP Qsync Central. The application fails to implement adequate limits or throttling mechanisms for resource consumption, which can be abused by an attacker with administrative privileges. When exploited, the attacker can monopolize system resources, causing resource starvation for other processes and legitimate users attempting to utilize synchronization services.

The attack requires network access and high-level privileges (administrator account), which limits the attack surface. However, once administrative access is obtained through credential theft, phishing, or other means, the exploitation is straightforward with no user interaction required. The vulnerability primarily impacts availability rather than confidentiality or integrity.

Root Cause

The root cause is the absence of proper resource allocation limits and throttling mechanisms (CWE-770 - Allocation of Resources Without Limits or Throttling). Qsync Central does not adequately constrain the amount of resources that can be consumed by administrative operations, allowing an authenticated administrator to request or consume resources without restriction.

Attack Vector

The attack is network-based and requires the attacker to first compromise or obtain legitimate administrator credentials for the Qsync Central application. Once authenticated with administrative privileges, the attacker can initiate operations that consume excessive resources without triggering protective throttling mechanisms. This can result in:

• Denial of service to legitimate synchronization operations
• System performance degradation
• Prevention of other applications from accessing required resources

The vulnerability does not enable code execution or data exfiltration but can disrupt the availability of synchronization services for all users.

Detection Methods for CVE-2025-58471

Indicators of Compromise

• Unusual resource consumption patterns from the Qsync Central process
• Multiple failed synchronization requests from legitimate users
• Administrator account activity from unexpected IP addresses or during unusual hours
• System resource exhaustion alerts coinciding with administrative sessions

Detection Strategies

• Monitor Qsync Central resource utilization for anomalous spikes in CPU, memory, or storage consumption
• Implement alerting for administrator login events from new or suspicious sources
• Track failed resource allocation events in system logs
• Configure SIEM rules to correlate administrator activity with resource exhaustion events

Monitoring Recommendations

• Enable verbose logging for administrative actions within Qsync Central
• Establish baseline metrics for normal resource consumption and alert on significant deviations
• Monitor network traffic for unusual patterns targeting the Qsync Central service
• Implement regular review of administrator account access logs

How to Mitigate CVE-2025-58471

Immediate Actions Required

• Update QNAP Qsync Central to version 5.2.0.1 (released 2025/12/21) or later immediately
• Audit administrator account usage and revoke unnecessary administrative privileges
• Review administrator account activity logs for suspicious behavior
• Implement multi-factor authentication for administrative access if available

Patch Information

QNAP has released a security update that addresses this vulnerability. The fix is included in Qsync Central version 5.2.0.1 and later releases. Administrators should consult the QNAP Security Advisory QSA-26-02 for complete remediation guidance and download instructions.

Workarounds

• Restrict administrative access to trusted IP addresses using firewall rules
• Implement network segmentation to limit exposure of Qsync Central to internal networks only
• Enforce strong password policies and regular credential rotation for administrator accounts
• Monitor and alert on resource consumption thresholds to detect potential exploitation attempts

# Example: Restrict Qsync Central admin access to specific IP range using firewall rules
# Adjust the IP range and interface according to your environment
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP