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QtsOperating system · Qnap

CVE-2023-23363

CRITICAL · 9.8 CVSS v3.1 Published 2023-09-22
Fix available
A fix is available. Upgrade to 4.3.3.2420 / 4.3.4.245 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 buffer copy without checking size of input vulnerability has been reported to affect QNAP operating system. If exploited, the vulnerability possibly allows remote users to execute code via unspecified vectors. We have already fixed the vulnerability in the following versions: QTS 4.3.6.2441 build 20230621 and later QTS 4.3.3.2420 build 20230621 and later QTS 4.2.6 build 20230621 and later QTS 4.3.4.2451 build 20230621 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 buffer copy without checking size vulnerability in QNAP operating system allows remote attackers to potentially execute arbitrary code via unspecified vectors. This is a classic buffer overflow where the application fails to validate input size before copying data into a fixed-size buffer.

MitigationApply the appropriate QTS firmware update (QTS 4.3.6.2441 build 20230621, QTS 4.3.3.2420 build 20230621, QTS 4.2.6 build 20230621, or QTS 4.3.4.2451 build 20230621 or later) to all affected QNAP devices. Prioritize externally accessible systems given the remote exploitation vector.

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, < 4.3.3.2420>= 4.3.4, < 4.3.4.245>= 4.3.6, < 4.3.6.2441

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. Access QNAP admin web interface
    Log into the QNAP device web console (typically https://[device-ip]:443 or :8080) and navigate to Control Panel > System Information > General. The QTS version is displayed on this page.
    Affected if The displayed QTS version falls within any of these ranges: 4.3.3 through 4.3.3.2419, 4.3.4 through 4.3.4.244, or 4.3.6 through 4.3.6.2440
  2. Check QTS version via command line
    If you have SSH or Telnet access to the QNAP device, connect and run: `getsysinfo system` or `cat /etc/version`. This outputs the installed QTS firmware version.
    Affected if The version output matches any of the affected ranges listed above
  3. Verify firmware build number
    In the admin interface, look for both the QTS version number (e.g., 4.3.6) AND the build number (e.g., 2440). The build number is shown in System Information > Firmware Version.
    Affected if The build number is lower than 2441 for QTS 4.3.6, lower than 2420 for QTS 4.3.3, or lower than 245 for QTS 4.3.4

A QNAP device is affected if it runs QTS firmware version 4.3.3.x below build 2420, 4.3.4.x below build 245, or 4.3.6.x below build 2441.

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 4.3.3.2420 / 4.3.4.245 / 4.3.6.2441 or later
Fixed in 4.3.3.24204.3.4.2454.3.6.2441
Interim mitigation

Apply the appropriate QTS firmware update (QTS 4.3.6.2441 build 20230621, QTS 4.3.3.2420 build 20230621, QTS 4.2.6 build 20230621, or QTS 4.3.4.2451 build 20230621 or later) to all affected QNAP devices. Prioritize externally accessible systems given the remote exploitation vector.

Recommended fix High confidence

QTS 4.3.6.2441 (or 4.3.3.2420, 4.3.4.2451, or 4.2.6 depending on current branch) build 20230621 or later

  1. 1. Log into the QNAP admin interface and check the current QTS version under Control Panel > System > Firmware Version
  2. 2. Determine which version branch your current QTS installation is on (4.2.6, 4.3.3, 4.3.4, or 4.3.6)
  3. 3. For QTS 4.3.6.x users: Upgrade to QTS 4.3.6.2441 build 20230621 or later
  4. 4. For QTS 4.3.3.x users: Upgrade to QTS 4.3.3.2420 build 20230621 or later
  5. 5. For QTS 4.3.4.x users: Upgrade to QTS 4.3.4.2451 build 20230621 or later
  6. 6. For QTS 4.2.6.x users: Upgrade to QTS 4.2.6 build 20230621 or later
  7. 7. Download the firmware from the QNAP download center and install via Control Panel > System > Firmware Update > Local Update
  8. 8. Verify the installed version matches the fixed release after reboot
Caveat Review QNAP App Center for app compatibility before upgrading; some legacy applications may require updates

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

Fix this in Qts Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2023-23363 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