CVE-2025-62854: Qnap File Station DOS Vulnerability

CVE-2025-62854 Overview

An uncontrolled resource consumption vulnerability has been reported to affect QNAP File Station 5. This denial-of-service (DoS) vulnerability allows authenticated remote attackers who have gained a user account to exploit the flaw and disrupt service availability. The vulnerability falls under CWE-400 (Uncontrolled Resource Consumption), which occurs when an application does not properly restrict the amount of resources consumed by an operation, potentially leading to service degradation or unavailability.

Critical Impact

Authenticated attackers can exploit this vulnerability to launch denial-of-service attacks against QNAP File Station 5 instances, potentially disrupting file sharing and management capabilities for organizations relying on QNAP NAS devices.

Affected Products

• QNAP File Station 5 versions prior to 5.5.6.5190
• QNAP NAS devices running vulnerable File Station 5 installations

Discovery Timeline

• 2026-02-11 - CVE-2025-62854 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2025-62854

Vulnerability Analysis

This vulnerability is classified as an uncontrolled resource consumption flaw (CWE-400). The weakness allows authenticated users to consume system resources without proper limitations, leading to denial-of-service conditions. The attack requires valid user credentials, which adds a barrier to exploitation but still poses a risk in environments where multiple users have access to the QNAP File Station interface.

The vulnerability specifically affects the File Station 5 application, which is QNAP's web-based file management utility that provides users with remote access to files stored on QNAP NAS devices. When exploited, the vulnerability can exhaust system resources, causing the File Station service to become unresponsive or crash.

Root Cause

The root cause stems from inadequate resource management within File Station 5. The application fails to properly limit resource allocation for certain operations, allowing authenticated users to trigger resource exhaustion scenarios. This type of vulnerability typically occurs when input parameters or request rates are not adequately validated or throttled.

Attack Vector

The attack is network-based, requiring the attacker to have authenticated access to the File Station 5 interface. Once authenticated, the attacker can send crafted requests that consume excessive system resources. The attack does not require user interaction and has low attack complexity, though the requirement for valid credentials limits the potential attacker pool.

The vulnerability mechanism involves sending requests to the File Station service that trigger uncontrolled resource consumption. This may manifest through operations that allocate memory, CPU cycles, or disk I/O without proper bounds checking or rate limiting. Technical details regarding specific exploitation methods can be found in the QNAP Security Advisory QSA-26-03.

Detection Methods for CVE-2025-62854

Indicators of Compromise

• Unusual resource consumption spikes on QNAP NAS devices running File Station 5
• File Station service becoming unresponsive or crashing unexpectedly
• Elevated memory or CPU usage correlated with authenticated user sessions
• Repeated connection attempts or high request volumes from specific user accounts

Detection Strategies

• Monitor system resource utilization metrics on QNAP devices for abnormal patterns
• Review File Station access logs for unusual activity patterns from authenticated users
• Implement network monitoring to detect high volumes of requests to File Station endpoints
• Enable alerting for File Station service crashes or restarts

Monitoring Recommendations

• Configure SNMP or syslog monitoring on QNAP devices to capture resource consumption metrics
• Set up baseline monitoring for normal File Station resource usage patterns
• Implement user activity logging to correlate resource spikes with specific accounts
• Monitor for repeated failed operations that may indicate exploitation attempts

How to Mitigate CVE-2025-62854

Immediate Actions Required

• Upgrade File Station 5 to version 5.5.6.5190 or later immediately
• Review and audit user accounts with access to File Station 5
• Implement network segmentation to limit access to QNAP management interfaces
• Monitor affected systems for signs of exploitation until patches are applied

Patch Information

QNAP has released a security update to address this vulnerability. The fix is included in File Station 5 version 5.5.6.5190 and later. Administrators should update their QNAP NAS devices through the App Center or by downloading the update directly from QNAP's website. For detailed patch information, refer to the QNAP Security Advisory QSA-26-03.

Workarounds

• Restrict File Station 5 access to trusted networks only using firewall rules
• Disable File Station 5 if not required until the patch can be applied
• Implement strong authentication policies and review user account permissions
• Consider using VPN access for remote File Station usage to add an authentication layer

# Example: Restrict access to File Station via QNAP firewall rules
# Access Control settings can be configured via:
# Control Panel > Security > Security Level > Allow connections from specific IP addresses only
# Add trusted IP ranges to limit exposure