CVE-2025-54152: QNAP Qsync Central Use-After-Free Bug

CVE-2025-54152 Overview

A use of out-of-range pointer offset vulnerability (CWE-823) has been identified in QNAP Qsync Central, a file synchronization application for QNAP NAS devices. This vulnerability allows authenticated remote attackers to read sensitive portions of memory by exploiting improper pointer boundary validation within the application.

Critical Impact

Authenticated attackers with valid user credentials can leverage this memory disclosure vulnerability to read sensitive memory contents, potentially exposing confidential data, credentials, or internal application state information stored in memory.

Affected Products

• QNAP Qsync Central versions prior to 5.0.0.4

Discovery Timeline

• 2026-01-20 - QNAP releases security patch in version 5.0.0.4
• 2026-02-11 - CVE-2025-54152 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2025-54152

Vulnerability Analysis

This vulnerability stems from improper handling of pointer offsets within QNAP Qsync Central. The application fails to properly validate pointer boundaries when processing certain operations, allowing memory access beyond intended buffer boundaries. When a remote attacker with valid user credentials exploits this flaw, they can induce the application to read memory contents from unintended locations, potentially disclosing sensitive information.

The attack requires network access and valid authentication credentials, limiting the exposure to authenticated users. However, once authenticated, exploitation does not require user interaction. The primary impact is to system availability with potential for information disclosure through memory reads.

Root Cause

The root cause of CVE-2025-54152 is a use of out-of-range pointer offset (CWE-823) vulnerability. This occurs when the application calculates pointer addresses using offset values that fall outside the valid memory range of the intended buffer or data structure. The application does not adequately validate that computed pointer offsets remain within legitimate bounds before dereferencing them, enabling attackers to read arbitrary memory locations.

Attack Vector

The attack vector for this vulnerability is network-based. An attacker must first obtain valid user credentials for Qsync Central, either through credential theft, phishing, or by leveraging compromised accounts. Once authenticated, the attacker can craft malicious requests that manipulate pointer offset calculations, causing the application to read memory beyond the intended boundaries.

The vulnerability mechanism involves sending specially crafted requests that influence pointer arithmetic operations within the application. When the application processes these requests without proper boundary validation, it accesses memory at attacker-controlled offsets, returning potentially sensitive data in the response.

Detection Methods for CVE-2025-54152

Indicators of Compromise

• Unusual memory access patterns or segmentation faults in Qsync Central logs
• Unexpected authentication attempts followed by abnormal API requests
• Application crashes or instability related to memory access violations
• Anomalous data in response payloads that may indicate memory disclosure

Detection Strategies

• Monitor Qsync Central application logs for repeated failed memory operations or crashes
• Implement network-level monitoring for unusual request patterns to the Qsync Central service
• Deploy endpoint detection to identify abnormal process behavior in the qsync service
• Review authentication logs for compromised credentials being used from unexpected sources

Monitoring Recommendations

• Enable verbose logging for Qsync Central to capture detailed request information
• Configure alerting for authentication anomalies and unusual service behavior
• Monitor system memory usage patterns for unexpected fluctuations in the Qsync Central process
• Implement SIEM rules to correlate authentication events with subsequent suspicious activity

How to Mitigate CVE-2025-54152

Immediate Actions Required

• Update QNAP Qsync Central to version 5.0.0.4 or later immediately
• Review access logs for any suspicious activity from authenticated users
• Audit user accounts and credentials with access to Qsync Central
• Consider restricting network access to Qsync Central to trusted networks only

Patch Information

QNAP has released a security patch addressing this vulnerability in Qsync Central version 5.0.0.4, released on 2026-01-20. Administrators should update to this version or later to remediate the vulnerability. The security advisory is available at the QNAP Security Advisory QSA-26-02.

Workarounds

• Limit network exposure by placing Qsync Central behind a firewall or VPN
• Implement strong authentication policies and multi-factor authentication where possible
• Reduce the attack surface by disabling Qsync Central if not actively required
• Monitor and restrict user account privileges to minimize potential exploitation impact

# Example: Restrict network access to Qsync Central service
# Add firewall rules to limit access to trusted networks only
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP