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QtsOperating system · Qnap

CVE-2021-28802

CRITICAL · 9.8 CVSS v3.1 Published 2021-07-01
Fix available
A fix is available. Upgrade to 4.5.1.1540 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
A command injection vulnerabilities have been reported to affect QTS and QuTS hero. If exploited, this vulnerability allows attackers to execute arbitrary commands in a compromised application. This issue affects: QNAP Systems Inc. QTS versions prior to 4.5.1.1540 build 20210107. QNAP Systems Inc. QuTS hero versions prior to h4.5.1.1582 build 20210217.

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 command injection vulnerability in QNAP QTS and QuTS hero allows remote attackers to execute arbitrary commands by injecting malicious commands through input fields or parameters that are not properly sanitized before being passed to system shell commands. This critical flaw affects QTS versions before 4.5.1.1540 build 20210107 and QuTS hero versions before h4.5.1.1582 build 20210217.

MitigationUpgrade QTS to version 4.5.1.1540 build 20210107 or later, and QuTS hero to version h4.5.1.1582 build 20210217 or later. Apply the latest security patches from QNAP and ensure the systems are not directly exposed to untrusted networks.

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:< 4.5.1.1540
Quts HeroOperating system
Affected:< h4.5.1.1582

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 product type
    Log into the QNAP admin web interface and check the Dashboard or System Information page to confirm whether the system is running QTS or QuTS hero. Alternatively, use the CLI command 'getsysinfo' or check '/etc/config/defsys.conf' if accessible via SSH.
    Affected if The product is QTS or QuTS hero (other QNAP products are not affected by this specific CVE)
  2. Check QTS version and build number
    In the QNAP admin interface, go to Control Panel > System > Firmware Update > View Firmware History, or use the CLI command 'ver'. Note both the version number (e.g., 4.5.1.x) and the build date.
    Affected if QTS version is below 4.5.1.1540, or the build date is before 20210107
  3. Check QuTS hero version and build number
    In the QuTS hero admin interface, go to Control Panel > System > Firmware Update > View Firmware History, or use the CLI command 'ver'. Note both the version number (starting with h4.5.1.x) and the build date.
    Affected if QuTS hero version is below h4.5.1.1582, or the build date is before 20210217
  4. Verify remote access exposure
    Check if the QNAP admin interface (port 808 or 443) is directly accessible from the internet or untrusted networks. Review firewall rules and port forwarding configurations on the local router or QNAP's built-in firewall (Security > Firewall).
    Affected if The admin interface is exposed to untrusted networks, increasing the likelihood of exploitation

The system is affected if it runs QTS versions before 4.5.1.1540 (build 20210107) or QuTS hero versions before h4.5.1.1582 (build 20210217), especially if the admin interface is internet-facing.

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 4.5.1.1540 or later
Fixed in 4.5.1.1540
Interim mitigation

Upgrade QTS to version 4.5.1.1540 build 20210107 or later, and QuTS hero to version h4.5.1.1582 build 20210217 or later. Apply the latest security patches from QNAP and ensure the systems are not directly exposed to untrusted networks.

Recommended fix High confidence

QTS 4.5.1.1540 (build 20210107) or QuTS hero h4.5.1.1582 (build 20210217)

  1. 1. Identify whether the system is running QTS or QuTS hero (log into the QNAP admin interface to confirm)
  2. 2. Backup all critical data on the NAS before proceeding with the firmware upgrade
  3. 3. Download the appropriate firmware update from the official QNAP download center: QTS 4.5.1.1540 (build 20210107) or QuTS hero h4.5.1.1582 (build 20210217)
  4. 4. In QNAP admin interface, go to Control Panel > System > Firmware Update
  5. 5. Select "Update Manually" and browse to the downloaded firmware file
  6. 6. Initiate the firmware update and wait for completion
  7. 7. After reboot, verify the firmware version matches the target build (20210107 for QTS or 20210217 for QuTS hero)
Caveat Firmware upgrades carry inherent risks including potential data loss; ensure full backup before proceeding

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

Fix this in Qts Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,180
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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-2021-28802 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