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QvrApplication · Qnap

CVE-2021-38686

HIGH · 8.8 CVSS v3.1 Published 2021-11-26
Fix available
A fix is available. Upgrade to 5.1.6 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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 QNAP device, VioStor. If exploited, this vulnerability allows attackers to compromise the security of the system. We have already fixed this vulnerability in the following versions of QVR: QVR FW 5.1.6 build 20211109 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

QNAP VioStor devices contain an improper authentication vulnerability that could allow remote attackers to bypass authentication mechanisms and compromise system security. The specific authentication flaw enables unauthorized access to the system.

MitigationUpdate QVR firmware to version 5.1.6 build 20211109 or later to remediate this vulnerability. If immediate patching is not possible, restrict network access to the VioStor management interface and monitor for unauthorized access attempts.

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:< 5.1.6

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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. Confirm QNAP VioStor device model
    Log into the QVR management interface or check the device label to confirm the device is a QNAP VioStor NVR system
    Affected if Device is a QNAP VioStor model running QVR firmware
  2. Check QVR firmware version
    In the QVR web interface, go to System Settings > System > Firmware or use the QNAP QVR Pro app to view the installed firmware version
    Affected if Firmware version displayed is below 5.1.6
  3. Compare version against affected range
    Note the full version number and build date, then compare against the vulnerable threshold of versions prior to 5.1.6 build 20211109
    Affected if Installed version is 5.1.5 or earlier, or the build date is before 20211109
  4. Verify remote access configuration
    Check if the QVR management interface is accessible from external networks by reviewing network settings and port forwarding rules on the router
    Affected if Remote management ports are open to the internet

A system is affected if it is a QNAP VioStor device running QVR firmware version below 5.1.6, particularly if the management interface is exposed to remote/network access.

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 QVR firmware to version 5.1.6 build 20211109 or later to remediate this vulnerability. If immediate patching is not possible, restrict network access to the VioStor management interface and monitor for unauthorized access attempts.

Recommended fix High confidence

QVR FW 5.1.6 build 20211109 or later

  1. 1. Identify the QNAP VioStor NVR device running QVR that needs updating
  2. 2. Check the current QVR firmware version via the QNAP admin interface (QVR > Settings > System > Firmware)
  3. 3. Navigate to the QNAP download center at www.qnap.com and download QVR FW 5.1.6 (build 20211109) or later for your specific device model
  4. 4. In the QVR admin interface, go to Settings > System > Firmware Update
  5. 5. Upload and apply the downloaded firmware update
  6. 6. After reboot, verify the firmware version shows 5.1.6 build 20211109 or later
Caveat Review QNAP release notes for QVR 5.1.6 to check for any configuration or feature changes that may affect your setup

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

Fix this in Qvr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2021-38686 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