CVE-2025-29876: Qnap File Station DoS Vulnerability

CVE-2025-29876 Overview

CVE-2025-29876 is a NULL pointer dereference vulnerability [CWE-476] affecting QNAP File Station 5. An authenticated remote attacker can trigger the flaw to cause a denial-of-service (DoS) condition on the affected service. Exploitation requires a valid user account but no user interaction, and the attack is delivered over the network. QNAP has resolved the issue in File Station 5 version 5.5.6.4847 and later. The vulnerability impacts availability only, with no confirmed impact on confidentiality or integrity. The flaw is documented in QNAP Security Advisory QSA-25-16.

Critical Impact
An authenticated remote attacker can crash File Station 5 and disrupt file access services for legitimate users.

Affected Products

QNAP File Station 5 versions prior to 5.5.6.4847
QNAP NAS appliances running vulnerable File Station 5 builds
Environments exposing File Station 5 to authenticated network users

Discovery Timeline

2025-06-06 - CVE-2025-29876 published to NVD
2025-06-18 - Last updated in NVD database

Technical Details for CVE-2025-29876

Vulnerability Analysis

The vulnerability is a NULL pointer dereference [CWE-476] in QNAP File Station 5. File Station 5 is the file-management web application bundled with QNAP NAS devices. The defect allows an authenticated user to send a request that causes the application to dereference a NULL pointer, terminating the service process. The result is a denial-of-service condition where File Station becomes unavailable until the service or device is restarted.

The attack vector is network-based and requires low privileges. No user interaction is needed once the attacker holds a valid account. The advisory does not report any impact on data confidentiality or integrity, and the resulting availability impact is limited to the File Station service.

Root Cause

The root cause is missing validation of a pointer before it is dereferenced in File Station 5 request handling. When the targeted code path receives input that leaves an internal pointer unset, the process accesses memory at a NULL address and crashes. QNAP corrected the logic in File Station 5 5.5.6.4847.

Attack Vector

An attacker with valid File Station credentials sends a crafted request over the network to the File Station 5 endpoint. The request reaches the vulnerable code path, triggers the NULL dereference, and terminates the service. Refer to QNAP Security Advisory QSA-25-16 for vendor technical context.

Detection Methods for CVE-2025-29876

Indicators of Compromise

Unexpected termination or repeated restarts of the File Station 5 service on QNAP NAS devices
Authenticated File Station HTTP/HTTPS requests immediately followed by service crash logs
Loss of File Station availability while other QNAP services continue running

Detection Strategies

Monitor QNAP system logs for File Station process crashes and abnormal exits
Correlate authenticated File Station session activity with service restart events
Alert on repeated authentication followed by short-lived sessions from the same source IP

Monitoring Recommendations

Forward QNAP NAS syslog and application logs to a central SIEM for correlation
Track the running version of File Station across the fleet and flag installations below 5.5.6.4847
Review File Station account inventory for stale or shared credentials that increase exploitation risk

How to Mitigate CVE-2025-29876

Immediate Actions Required

Update File Station 5 to version 5.5.6.4847 or later on all QNAP NAS devices
Restrict File Station 5 network exposure to trusted networks and VPN users only
Audit File Station user accounts and revoke unused or low-trust credentials
Enforce strong, unique passwords and multi-factor authentication for QNAP accounts

Patch Information

QNAP has fixed the vulnerability in File Station 5 5.5.6.4847 and later. Apply the update through the QNAP App Center or download it from the vendor advisory at QNAP Security Advisory QSA-25-16.

Workarounds

Disable File Station 5 on devices where the application is not required until patching completes
Place QNAP NAS management interfaces behind a firewall or VPN to limit authenticated reach
Limit File Station access to administrative accounts while planning the upgrade

bash

# Verify installed File Station version on a QNAP NAS via SSH
# Replace the path if your firmware stores QPKG metadata elsewhere
cat /etc/config/qpkg.conf | grep -A2 -i 'filestation'

# Example: confirm the version is 5.5.6.4847 or later before considering the device patched