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QtsOperating system · Qnap

CVE-2021-28816

HIGH · 8.8 CVSS v3.1 Published 2021-09-10
Fix available
A fix is available. Upgrade to 4.3.3.1693 / 4.3.6.1750 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
A stack buffer overflow vulnerability has been reported to affect QNAP device running QTS, QuTScloud, QuTS hero. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of QTS, QuTScloud, QuTS hero: QTS 4.5.4.1715 build 20210630 and later QTS 5.0.0.1716 build 20210701 and later QTS 4.3.3.1693 build 20210624 and later QTS 4.3.6.1750 build 20210730 and later QuTScloud c4.5.6.1755 and later QuTS hero h4.5.4.1771 build 20210825 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 · high confidence

A stack buffer overflow vulnerability in QNAP QTS, QuTScloud, and QuTS hero allows remote attackers to execute arbitrary code. This high-severity (CVSS 8.8) flaw is exploitable over the network and affects multiple QNAP firmware versions.

MitigationUpgrade affected QNAP devices to the specified fixed versions: QTS 4.5.4.1715+, QTS 5.0.0.1716+, QTS 4.3.3.1693+, QTS 4.3.6.1750+, QuTScloud c4.5.6.1755+, or QuTS hero h4.5.4.1771+.

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
QtsOperating system
Affected:< 4.3.3.1693>= 4.3.4, < 4.3.6.1750>= 4.4.0, < 4.5.4.1715>= 5.0.0, < 5.0.0.1716
Quts HeroOperating system
Affected:< h4.5.4.1771
QutscloudOperating system
Affected:< c4.5.6.1755

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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. Check QTS firmware version via web UI
    Log into the QNAP web console, go to Control Panel > System > Firmware Update, or check Control Panel > System Status > System Information to view the current QTS version.
    Affected if The version falls into any of these ranges: < 4.3.3.1693; >= 4.3.4 and < 4.3.6.1750; >= 4.4.0 and < 4.5.4.1715; >= 5.0.0 and < 5.0.0.1716
  2. Check QuTS hero firmware version via web UI
    Log into the QuTS hero web console and navigate to Control Panel > System > System Information to view the firmware version.
    Affected if The version is lower than h4.5.4.1771
  3. Check QuTScloud firmware version via command line
    Access the QuTScloud instance via SSH and run the command 'version' or check the cloud console for the installed QuTScloud version.
    Affected if The version is lower than c4.5.6.1755
  4. Verify network accessibility of the QNAP device
    Confirm that the QNAP admin interface (ports 443 or 8080) is accessible from network sources, since this vulnerability is exploitable over the network.
    Affected if The QNAP management interface is exposed to untrusted networks and the firmware version is in any of the affected ranges listed above.

You are affected if your QNAP device is running any QTS, QuTS hero, or QuTScloud version below the fixed releases and the management interface is network-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 4.3.3.1693 / 4.3.6.1750 / 4.5.4.1715 or later
Fixed in 4.3.3.16934.3.6.17504.5.4.1715
Interim mitigation

Upgrade affected QNAP devices to the specified fixed versions: QTS 4.5.4.1715+, QTS 5.0.0.1716+, QTS 4.3.3.1693+, QTS 4.3.6.1750+, QuTScloud c4.5.6.1755+, or QuTS hero h4.5.4.1771+.

Recommended fix High confidence

Upgrade to QTS 4.5.4.1715+ (or 4.3.6.1750+, 4.3.3.1693+, 5.0.0.1716+), QuTScloud c4.5.6.1755+, or QuTS hero h4.5.4.1771+ depending on current branch

  1. 1. Identify the current QTS, QuTScloud, or QuTS hero version running on the QNAP device via the control panel or System Administration > Firmware Update
  2. 2. Determine the appropriate upgrade path based on current version (see upgrade_path field)
  3. 3. Access QNAP Device via the administrative web interface
  4. 4. Navigate to Control Panel > System > Firmware Update or System Administration > Firmware Update
  5. 5. Click 'Check for Update' to see available updates
  6. 6. Select and install the appropriate fixed version: QTS 4.5.4.1715 (or later), QTS 5.0.0.1716 (or later), QTS 4.3.3.1693 (or later), QTS 4.3.6.1750 (or later), QuTScloud c4.5.6.1755 (or later), or QuTS hero h4.5.4.1771 (or later)
  7. 7. Wait for the firmware update to complete and the device to reboot
  8. 8. Verify the new version is installed by checking System Administration > Firmware Update > Version Information
Caveat Firmware updates may require downtime and should be tested in a non-production environment first; ensure data backups exist before applying updates

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

Fix this in Qts Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2021-28816 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
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