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QvrApplication · Qnap

CVE-2025-52856

CRITICAL · 9.8 CVSS v3.1 Published 2025-08-29
Fix available
A fix is available. Upgrade to 5.1.6 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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 improper authentication vulnerability has been reported to affect VioStor. If a remote attacker, they can then exploit the vulnerability to compromise the security of the system. We have already fixed the vulnerability in the following version: VioStor 5.1.6 build 20250621 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

Improper authentication vulnerability in VioStor video surveillance software allows remote attackers to bypass authentication mechanisms and compromise system security.

MitigationUpdate VioStor to version 5.1.6 build 20250621 or later to remediate the vulnerability.

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
QvrApplication
Affected:>= 5.1.0, < 5.1.6= 5.1.6

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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. Identify Qnap Qvr / VioStor installation
    Locate the VioStor video surveillance software or Qnap Qvr application in your environment. Confirm the product name and that it is a Qnap surveillance system.
    Affected if The system is running Qnap Qvr or VioStor video surveillance software.
  2. Determine installed version
    Access the Qnap admin interface or use system information commands to find the installed version of the Qvr/VioStor software. Look for a version number in the format such as 5.1.x.
    Affected if The version cannot be determined or is not visible in the system.
  3. Compare version to affected range
    Compare the installed version number against the affected range: versions >= 5.1.0 and < 5.1.6, or version 5.1.6 (prior to build 20250621).
    Affected if The installed version is 5.1.0 through 5.1.5 (any build), or is exactly 5.1.6 but predates build 20250621.
  4. Verify authentication configuration
    Check if remote access or network-based authentication is enabled for the surveillance system, as this vulnerability allows bypassing authentication mechanisms.
    Affected if Remote or network-based authentication is enabled and the version falls within the affected range.

The system is affected if Qnap Qvr or VioStor is installed with a version from 5.1.0 up to 5.1.6 (prior to build 20250621), and remote authentication is accessible.

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 5.1.6 or later
Fixed in 5.1.6
Interim mitigation

Update VioStor to version 5.1.6 build 20250621 or later to remediate the vulnerability.

Recommended fix High confidence

VioStor 5.1.6 build 20250621 or later

  1. 1. Log in to the QNAP NAS as an administrator.
  2. 2. Open App Center and locate Qvr (or VioStor).
  3. 3. Check the current installed version of Qvr/VioStor in the application details.
  4. 4. If the installed version is below 5.1.6 build 20250621, proceed with the update.
  5. 5. In App Center, click Update on Qvr/VioStor to install the latest available version.
  6. 6. Alternatively, download the latest Qvr version from the QNAP download center and manually install it.
  7. 7. After updating, verify the version shows 5.1.6 build 20250621 or later to confirm the vulnerability is patched.

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

Fix this in Qvr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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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-2025-52856 in production — separate from our analysis above.

No notes yet

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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