CVE-2025-54170: Qnap Qsync Central Information Disclosure

CVE-2025-54170 Overview

An out-of-bounds read vulnerability has been identified in QNAP Qsync Central, a file synchronization application used on QNAP NAS devices. This memory safety flaw allows authenticated remote attackers to read data beyond the intended memory boundaries, potentially exposing sensitive information stored on the affected system.

The vulnerability requires an attacker to first gain access to a valid user account. Once authenticated, they can exploit the out-of-bounds read condition to obtain secret data that should not be accessible. This type of vulnerability (CWE-125) occurs when software reads data past the end or before the beginning of the intended buffer, which can lead to exposure of sensitive memory contents.

Critical Impact

Authenticated attackers can exploit this vulnerability to read sensitive data from memory, potentially compromising confidential information stored on QNAP NAS devices running vulnerable versions of Qsync Central.

Affected Products

• QNAP Qsync Central versions prior to 5.0.0.4
• QNAP NAS devices running vulnerable Qsync Central installations

Discovery Timeline

• February 11, 2026 - CVE-2025-54170 published to NVD
• February 12, 2026 - Last updated in NVD database

Technical Details for CVE-2025-54170

Vulnerability Analysis

This out-of-bounds read vulnerability exists within QNAP's Qsync Central application, which provides file synchronization capabilities across QNAP NAS devices and connected clients. The vulnerability is classified under CWE-125 (Out-of-bounds Read), indicating that the software fails to properly validate memory access boundaries during certain operations.

When exploited, the vulnerability allows an authenticated attacker to read memory contents beyond the allocated buffer boundaries. This can result in the disclosure of sensitive information that resides in adjacent memory locations, including potentially cryptographic keys, session tokens, configuration data, or other confidential information.

The attack requires network access and valid user credentials, limiting the immediate exposure to unauthenticated attackers. However, the high confidentiality impact means that successful exploitation can lead to significant data exposure.

Root Cause

The root cause stems from improper boundary validation when reading data within the Qsync Central application. The software fails to adequately verify that read operations remain within the intended memory buffer limits, allowing access to adjacent memory regions that may contain sensitive data.

This type of vulnerability typically arises from missing or insufficient bounds checking in code paths that handle variable-length data or array indexing operations. Without proper validation, an attacker can craft requests that cause the application to read beyond the allocated buffer.

Attack Vector

The attack is network-based and requires the attacker to have authenticated access to the system. The exploitation flow involves:

1. The attacker obtains valid credentials for a Qsync Central user account (through phishing, credential stuffing, or other means)
2. Using authenticated access, the attacker sends specially crafted requests to the Qsync Central service
3. The vulnerable code processes the request without proper bounds checking
4. Memory contents beyond the intended buffer are read and returned to the attacker
5. The attacker extracts sensitive information from the leaked memory data

The vulnerability does not require user interaction beyond the initial authentication, and the attack complexity is considered low once valid credentials are obtained.

Detection Methods for CVE-2025-54170

Indicators of Compromise

• Unusual memory read patterns or access violations in Qsync Central logs
• Authenticated sessions exhibiting abnormal data retrieval patterns
• Network traffic containing malformed or oversized requests to Qsync Central services
• Error messages indicating buffer read anomalies in application logs

Detection Strategies

• Monitor Qsync Central service logs for unexpected error conditions or access violations
• Implement network-level monitoring for suspicious authenticated session behavior
• Deploy intrusion detection rules to identify exploitation attempts targeting Qsync Central
• Use file integrity monitoring on QNAP systems to detect potential data exfiltration

Monitoring Recommendations

• Enable verbose logging on Qsync Central services to capture detailed request information
• Configure alerts for multiple failed authentication attempts followed by unusual data access
• Implement network traffic analysis to identify patterns consistent with memory disclosure attacks
• Review user account activity regularly for signs of compromise or credential theft

How to Mitigate CVE-2025-54170

Immediate Actions Required

• Update QNAP Qsync Central to version 5.0.0.4 or later immediately
• Review user accounts for unauthorized access and reset credentials if compromise is suspected
• Restrict network access to Qsync Central services to trusted networks only
• Implement strong authentication requirements including multi-factor authentication where possible

Patch Information

QNAP has released a security update addressing this vulnerability. The fix is available in Qsync Central version 5.0.0.4 (released January 20, 2026) and later versions. Administrators should update through the QNAP App Center or download the update from the QNAP Security Advisory QSA-26-02.

To update:

1. Log into your QNAP NAS administration interface
2. Navigate to App Center
3. Locate Qsync Central in your installed applications
4. Apply the available update to version 5.0.0.4 or later

Workarounds

• Limit network exposure of Qsync Central services using firewall rules
• Disable Qsync Central if not actively required until patching can be completed
• Implement network segmentation to isolate QNAP NAS devices from untrusted networks
• Enable IP access control lists to restrict connections to known trusted hosts

# Example: Restrict access to Qsync Central port using iptables
# Replace 8080 with your actual Qsync Central port
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP