CVE-2025-30275 Overview
CVE-2025-30275 is a NULL pointer dereference vulnerability [CWE-476] affecting QNAP Qsync Central. An authenticated remote attacker with a valid user account can trigger the flaw to cause a denial-of-service (DoS) condition on the affected service. QNAP disclosed the issue in security advisory QSA-25-22 and released a fix in Qsync Central 4.5.0.7 on April 23, 2025. The vulnerability requires network access and low privileges but no user interaction. Exploitation impacts service availability without affecting confidentiality or integrity.
Critical Impact
Authenticated remote attackers can crash the Qsync Central service, disrupting file synchronization for all connected clients.
Affected Products
- QNAP Qsync Central versions prior to 4.5.0.7
- QNAP NAS devices running vulnerable Qsync Central builds
- Environments relying on Qsync Central for centralized file synchronization
Discovery Timeline
- 2025/04/23 - QNAP releases Qsync Central 4.5.0.7 with the fix
- 2025-08-29 - CVE-2025-30275 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-30275
Vulnerability Analysis
The flaw is a NULL pointer dereference [CWE-476] in QNAP Qsync Central. Qsync Central is a centralized file synchronization application that runs on QNAP NAS appliances and coordinates sync operations for multiple client devices. When the vulnerable code path receives specific input from an authenticated user, it dereferences a pointer without validating that it references a valid memory address. The resulting segmentation fault terminates the affected process or worker thread.
The outcome is loss of availability for the Qsync Central service. File synchronization across connected endpoints stops until the service is restarted. QNAP has not published detailed exploitation mechanics beyond the advisory summary.
Root Cause
The root cause is missing input or state validation before pointer dereference. The application assumes an object or handle is initialized when handling a request from a low-privileged user session. When that assumption fails, the process reads or writes through a NULL pointer and crashes. Consult the QNAP Security Advisory QSA-25-22 for vendor-supplied context.
Attack Vector
Exploitation requires network reachability to the Qsync Central service and a valid low-privileged user account. The attacker sends a crafted request that triggers the unchecked pointer path. No user interaction is required on the target. Because credentials are needed, exposure is limited to environments where user accounts exist or can be obtained through credential compromise. Repeated exploitation produces a sustained denial-of-service condition against Qsync Central operations.
Detection Methods for CVE-2025-30275
Indicators of Compromise
- Unexpected termination or repeated restarts of the Qsync Central service on the NAS
- Segmentation fault or crash entries in QNAP system logs correlated with Qsync Central worker processes
- Interruption of file synchronization for multiple clients without a corresponding administrative action
- Authenticated sessions from unusual source addresses immediately preceding service crashes
Detection Strategies
- Monitor QNAP system and application logs for crash events tied to Qsync Central processes
- Correlate authenticated user session activity with Qsync Central service restarts to identify abuse patterns
- Baseline normal Qsync Central uptime and alert on abnormal termination frequency
- Track failed and successful logins to Qsync Central to identify low-privileged accounts exhibiting anomalous request patterns
Monitoring Recommendations
- Forward QNAP NAS logs to a centralized logging or SIEM platform for retention and correlation
- Alert on repeated Qsync Central service restarts within a short time window
- Review Qsync Central user account inventory and disable unused accounts to reduce the attack surface
- Monitor network access controls to ensure the Qsync Central management interface is not exposed to untrusted networks
How to Mitigate CVE-2025-30275
Immediate Actions Required
- Upgrade Qsync Central to version 4.5.0.7 or later on all QNAP NAS devices
- Inventory all Qsync Central user accounts and remove unused or shared credentials
- Restrict network access to Qsync Central management interfaces to trusted networks only
- Review authentication logs for anomalous or brute-force activity against Qsync Central
Patch Information
QNAP fixed the vulnerability in Qsync Central 4.5.0.7, released on 2025/04/23. Administrators should apply the update through the App Center on affected QNAP NAS devices. Refer to the QNAP Security Advisory QSA-25-22 for the official fixed-version guidance and download instructions.
Workarounds
- Disable Qsync Central on affected NAS devices until the patch can be applied
- Enforce strong password policies and multi-factor authentication for all NAS user accounts
- Place the NAS behind a VPN or firewall rule that limits access to trusted client subnets
- Reduce the number of accounts with Qsync Central access to the minimum required for operations
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
