CVE-2025-29877: Qnap File Station DoS Vulnerability

CVE-2025-29877 Overview

CVE-2025-29877 is a NULL pointer dereference vulnerability [CWE-476] affecting QNAP File Station 5. A remote attacker with valid user credentials can trigger the flaw to cause a denial-of-service (DoS) condition on the affected system. QNAP disclosed the issue in security advisory QSA-25-16 and has released a fix in File Station 5 version 5.5.6.4847 and later.

The vulnerability is network-exploitable and requires low privileges with no user interaction. Exploitation impacts service availability but does not affect confidentiality or integrity of stored data.

Critical Impact
Authenticated remote attackers can crash the File Station 5 service, disrupting file access for legitimate users on affected QNAP NAS deployments.

Affected Products

QNAP File Station 5 versions prior to 5.5.6.4847
QNAP NAS appliances running vulnerable File Station 5 builds
Deployments exposing File Station to networks accessible by authenticated users

Discovery Timeline

2025-06-06 - CVE-2025-29877 published to NVD
2025-06-06 - QNAP releases security advisory QSA-25-16 with fixed version 5.5.6.4847
2025-06-18 - Last updated in NVD database

Technical Details for CVE-2025-29877

Vulnerability Analysis

The vulnerability is a NULL pointer dereference within QNAP File Station 5, a web-based file management application bundled with QNAP NAS devices. When a specific request path is processed by the application, code reads from a pointer that has not been initialized or has been freed. The dereference triggers a segmentation fault, terminating the responsible process or worker thread.

The attack requires network reachability to the File Station web interface and a valid user account. Privilege requirements are low, meaning any authenticated user, including non-administrative accounts, can trigger the condition. Successful exploitation produces a denial-of-service outcome against File Station availability without compromising stored files or user credentials.

QNAP has not published exploit code, and no public proof-of-concept is available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Root Cause

The root cause is missing validation of a pointer before dereference, classified under [CWE-476]. The application fails to verify that an internal object or buffer was successfully allocated or correctly populated before code accesses its members. When the pointer is NULL, the resulting memory access fault terminates the process handling the request.

Attack Vector

An authenticated attacker sends a crafted HTTP request to the File Station 5 endpoint over the network. The request causes the vulnerable code path to dereference a NULL pointer, crashing the service. Repeated requests sustain the denial-of-service condition and prevent legitimate users from accessing files through File Station until the service is restarted.

The vulnerability is described in prose only. QNAP did not publish exploit code or technical reproduction steps. See the QNAP Security Advisory QSA-25-16 for vendor-provided details.

Detection Methods for CVE-2025-29877

Indicators of Compromise

Unexpected crashes or restarts of the File Station 5 process on QNAP NAS appliances
HTTP 5xx errors returned from File Station endpoints following authenticated requests
Repeated request patterns from a single authenticated session immediately preceding a service failure
Entries in QNAP system logs indicating abnormal termination of the File Station service

Detection Strategies

Monitor QNAP system event logs for File Station service crashes and automatic restarts
Correlate authenticated File Station HTTP requests with subsequent service termination events
Alert on bursts of File Station API requests from a single user account that coincide with availability loss

Monitoring Recommendations

Ingest QNAP NAS syslog and audit data into a centralized SIEM for continuous review
Track the running version of File Station across the NAS fleet and flag systems below 5.5.6.4847
Review File Station access logs for authentication anomalies, including newly created or rarely used accounts issuing administrative requests

How to Mitigate CVE-2025-29877

Immediate Actions Required

Upgrade File Station 5 to version 5.5.6.4847 or later on all QNAP NAS appliances
Audit File Station user accounts and disable any accounts that are unused or no longer required
Restrict File Station network exposure to trusted internal networks and VPN clients only
Enforce strong password and multi-factor authentication policies for QNAP user accounts

Patch Information

QNAP has released a fixed build of File Station 5 in version 5.5.6.4847 and later. Administrators should sign in to QuTS hero or QTS, open the App Center, search for File Station 5, and apply the update. Refer to QNAP Security Advisory QSA-25-16 for vendor instructions.

Workarounds

Limit File Station access to a defined IP allowlist using the QNAP firewall or upstream network controls
Remove File Station permissions from non-essential user accounts until the patch is applied
Place QNAP NAS appliances behind a VPN and block direct internet exposure of the File Station web interface

bash

# Verify installed File Station 5 version on a QNAP NAS via SSH
# Replace with your actual NAS hostname or IP
ssh admin@<nas-host> "qpkg_cli --list | grep -i 'File Station 5'"

# Expected: version 5.5.6.4847 or later