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Qsync CentralApplication · Qnap

CVE-2025-54151

MEDIUM · 5.5 CVSS v3.1 Published 2026-02-11
Fix available
A fix is available. Upgrade to 5.0.0.4 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An uncontrolled resource consumption vulnerability has been reported to affect Qsync Central. If a local attacker gains a user account, they can then exploit the vulnerability to launch a denial-of-service (DoS) attack. We have already fixed the vulnerability in the following version: Qsync Central 5.0.0.4 ( 2026/01/20 ) and later

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is an uncontrolled resource consumption vulnerability in Qsync Central (a QNAP file sync product) where a local authenticated user can exhaust system resources (CPU, memory, disk, or connections) leading to denial of service. The attacker requires valid user credentials to exploit the flaw.

MitigationUpgrade Qsync Central to version 5.0.0.4 or later. Until upgrade, limit and monitor user account usage, and implement network-level rate limiting or resource quotas where possible.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Qsync CentralApplication
Affected:>= 5.0.0.0, < 5.0.0.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate Qsync Central version in QNAP interface
    Log into the QNAP admin web interface, navigate to App Center, find Qsync Central in the installed applications list, and note the version number displayed.
    Affected if The displayed version is 5.0.0.0, 5.0.0.1, 5.0.0.2, or 5.0.0.3 (any version from 5.0.0.0 up to but not including 5.0.0.4).
  2. Check Qsync Central version via command line
    If SSH access is available to the QNAP device, access the command line and query the installed package version using the QPKG management command: qpkg -e Qsync_Central or check /share/CACHEDEV1_DATA/.qpkg/Qsync_Central for version info.
    Affected if The command returns a version number within the 5.0.0.0 to 5.0.0.3 range.
  3. Confirm user authentication is enabled for Qsync
    In the QNAP admin interface, go to Qsync Central settings and verify that user account authentication is configured and active. Check that local users or domain users can log into Qsync.
    Affected if User authentication is enabled and active, making the exploitation prerequisite (valid credentials) achievable.
  4. Review Qsync Central system logs for resource exhaustion
    Access Qsync Central logs via the web interface or command line (typically in /share/CACHEDEV1_DATA/.qpkg/Qsync_Central/logs/) and search for repeated connection events, high CPU/memory indicators, or error messages indicating service slowdown.
    Affected if Logs show patterns of resource exhaustion, connection limits, or service degradation that could indicate active exploitation.

You are affected if Qsync Central is installed with any version from 5.0.0.0 through 5.0.0.3, user authentication is enabled, and you observe resource exhaustion symptoms or have authenticated users who could potentially trigger the vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.0.0.4 or later
Fixed in 5.0.0.4
Interim mitigation

Upgrade Qsync Central to version 5.0.0.4 or later. Until upgrade, limit and monitor user account usage, and implement network-level rate limiting or resource quotas where possible.

Recommended fix High confidence

Qsync Central 5.0.0.4

  1. Identify the current version of Qsync Central installed on the system
  2. Navigate to the QNAP download center at www.qnap.com and locate Qsync Central version 5.0.0.4 or later
  3. Download the updated Qsync Central installation package
  4. Follow QNAP's standard firmware/software update procedure to install version 5.0.0.4
  5. Verify the installation was successful and the system is running version 5.0.0.4 or later

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Qsync Central Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-54151 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data