CVE-2021-34345
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 · uneditedA stack buffer overflow vulnerability has been reported to affect QNAP device running NVR Storage Expansion. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of NVR Storage Expansion: NVR Storage Expansion 1.0.6 ( 2021/08/03 ) 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 confidenceA stack buffer overflow vulnerability in QNAP NVR Storage Expansion allows remote attackers to execute arbitrary code via crafted network requests. The vulnerability stems from insufficient bounds checking when processing input on the stack, enabling attackers to overwrite return addresses and inject malicious code.
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< 1.0.6< 1.0.6< 1.0.6< 1.0.6< 1.0.6< 1.0.6< 1.0.6< 1.0.6CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the QNAP device modelAccess the QNAP admin interface (typically via web browser at the device's IP address) and navigate to the System Settings or Control Panel to locate the exact model name (e.g., Ej1600, Tl R1620sdc, Tl D1600s, etc.). Alternatively, check the physical device label or use the QNAP Finder utility on the local network.Affected if The model matches any of the following: Ej1600, Tl R1620sdc, Tl R1620sep Rp, Tl R1220sep Rp, Tl D1600s, Tl D800s, Tl D400s, or Tl R1200s Rp.
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Check the installed firmware versionIn the QNAP admin interface, go to Control Panel > System > Firmware Update (or System Settings > Firmware) to view the current firmware version. Alternatively, access the device via SSH and run the command: cat /etc/config/defect_info or check the version via the QNAP web interface.Affected if The firmware version is displayed as a number lower than 1.0.6 (e.g., 1.0.5, 1.0.4, etc.).
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Verify if NVR Storage Expansion is enabledIn the QNAP admin interface, navigate to Storage & Snapshots (or Storage Manager) and look for NVR Storage Expansion settings. Check whether the NVR Storage Expansion feature is actively configured or mounted. If accessing via CLI, check for processes or services related to NVR expansion.Affected if The NVR Storage Expansion feature is enabled, configured, or actively running on the device.
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Confirm network exposure of the deviceCheck the network configuration to determine if the device is directly accessible from the internet or an untrusted network. Review port forwarding rules on your router, firewall policies, and the device's own access control settings (found in Control Panel > Security).Affected if The device is reachable from untrusted networks (e.g., has open management ports exposed to the internet or is on a poorly segmented network).
A user is affected if they have a QNAP Ej1600, Tl R1620sdc, Tl R1620sep Rp, Tl R1220sep Rp, Tl D1600s, Tl D800s, Tl D400s, or Tl R1200s Rp device running firmware version below 1.0.6 with the NVR Storage Expansion feature enabled and accessible over the network.
Generated from the published advisory. Verify against your own configuration.
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 · scoped1.0.6
Update NVR Storage Expansion to version 1.0.6 or later. If immediate patching is not possible, restrict network exposure by placing affected devices behind a firewall or VPN, limiting access to trusted IP addresses only.
NVR Storage Expansion 1.0.6 or later (released 2021/08/03)
- 1. Identify the exact model of your QNAP device from the affected list (Ej1600, Tl R1620sdc, Tl R1620sep Rp, Tl R1220sep Rp, Tl D1600s, Tl D800s, Tl D400s, Tl R1200s Rp)
- 2. Access the QNAP admin interface for your device
- 3. Navigate to the NVR Storage Expansion application settings
- 4. Check the current firmware version of NVR Storage Expansion
- 5. If version is below 1.0.6, initiate the firmware update to version 1.0.6 or later
- 6. Verify the update was successful by confirming the installed version is 1.0.6 or higher
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-34345 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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