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QtsOperating system · Qnap

CVE-2021-38674

MEDIUM · 6.1 CVSS v3.1 Published 2022-01-07
Fix available
A fix is available. Upgrade to 4.5.4.1787 or later.
See remediation →
68/100
Remediation priority · Elevated
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
A cross-site scripting (XSS) vulnerability has been reported to affect QTS, QuTS hero and QuTScloud. If exploited, this vulnerability allows remote attackers to inject malicious code. We have already fixed this vulnerability in the following versions of QTS, QuTS hero and QuTScloud: QuTS hero h4.5.4.1771 build 20210825 and later QTS 4.5.4.1787 build 20210910 and later QuTScloud c4.5.7.1864 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

A cross-site scripting (XSS) vulnerability in QNAP QTS, QuTS hero, and QuTScloud web interfaces allows remote attackers to inject malicious script code through unspecified input vectors. The vulnerability affects the administrative interface of these NAS operating systems.

MitigationUpdate to the fixed versions: QTS 4.5.4.1787+, QuTS hero h4.5.4.1771+, or QuTScloud c4.5.7.1864+. Review the admin interface for any unexpected user inputs or stored scripts as a precautionary measure.

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:< 4.5.4.1787
Quts HeroOperating system
Affected:< h4.5.4.1771
QutscloudOperating system
Affected:< c4.5.7.1864

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
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

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 the QNAP product type
    Access the NAS admin interface and navigate to Control Panel > System > System Status, or run 'cat /proc/bootfs' via SSH to determine if the system is running QTS, QuTS hero, or QuTScloud
    Affected if The product is QTS, QuTS hero, or QuTScloud (any of these are affected)
  2. Check QTS version
    In the admin interface, go to Control Panel > System > System Status to view the firmware version. Alternatively, run 'fw_util.sh sys_info' via SSH
    Affected if The displayed version is below 4.5.4.1787
  3. Check QuTS hero version
    In the admin interface, go to Control Panel > System > System Status to view the firmware version. Alternatively, check the /etc/config/version file via SSH
    Affected if The displayed version is below h4.5.4.1771
  4. Check QuTScloud version
    Access the QuTScloud management portal or check the version via the cloud control panel interface
    Affected if The displayed version is below c4.5.7.1864
  5. Confirm web interface is accessible
    Verify the administrative web interface is enabled and reachable by attempting to access the NAS IP on ports 8080 or 443. The vulnerability exists in the web interface component.
    Affected if The admin web interface is enabled and the version is below the fixed releases

You are affected if your QTS version is below 4.5.4.1787, QuTS hero is below h4.5.4.1771, or QuTScloud is below c4.5.7.1864 and the admin web interface 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 4.5.4.1787 or later
Fixed in 4.5.4.1787
Interim mitigation

Update to the fixed versions: QTS 4.5.4.1787+, QuTS hero h4.5.4.1771+, or QuTScloud c4.5.7.1864+. Review the admin interface for any unexpected user inputs or stored scripts as a precautionary measure.

Recommended fix High confidence

QTS 4.5.4.1787 (build 20210910+) | QuTS hero h4.5.4.1771 (build 20210825+) | QuTScloud c4.5.7.1864 (build 20211027+)

  1. 1. Back up all critical data on the NAS before performing any firmware upgrade
  2. 2. Log in to the QNAP admin interface (QTS, QuTS hero, or QuTScloud)
  3. 3. Navigate to Control Panel > System > Firmware Update
  4. 4. Select 'Check for Update' to identify the latest available version
  5. 5. Download and install the appropriate fixed version: QTS 4.5.4.1787 (build 20210910 or later), QuTS hero h4.5.4.1771 (build 20210825 or later), or QuTScloud c4.5.7.1864 (build 20211027 or later)
  6. 6. Allow the firmware update to complete and the system to reboot
  7. 7. Verify the firmware version after reboot matches the fixed release
Caveat Firmware upgrades carry inherent risk; always backup data before updating QNAP NAS firmware

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

Fix this in Qts 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
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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-2021-38674 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