CVE-2021-20161
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 · uneditedTrendnet AC2600 TEW-827DRU version 2.08B01 does not have sufficient protections for the UART functionality. A malicious actor with physical access to the device is able to connect to the UART port via a serial connection. No username or password is required and the user is given a root shell with full control of the device.
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 confidenceTrendnet AC2600 TEW-827DRU firmware 2.08B01 contains an exposed UART serial interface that requires no authentication. A physical attacker with serial console access can connect directly to the UART port and obtain an unauthenticated root shell, gaining full control of the device.
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= 2.08b01CVSS 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
- Physical
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:P/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 device modelLocate the device and verify it is a Trendnet AC2600 TEW-827DRU router by checking the physical label or web interfaceAffected if device is not a TEW-827DRU (not affected)
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Check firmware versionAccess the router web interface (typically 192.168.1.1) and navigate to Status or Firmware section to confirm the installed firmware version is 2.08B01Affected if firmware version is not exactly 2.08B01 (not affected)
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Inspect UART interface accessibilityPower down the device, open the enclosure, and examine the circuit board for exposed UART (serial) header pins - typically a 4-6 pin header near the edge of the boardAffected if UART pins are physically exposed and accessible on the circuit board (potentially affected)
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Verify physical security controlsDetermine if the device is located in a restricted area where unauthorized physical access is prevented, and check if the enclosure shows signs of tamperingAffected if device is in an unsecured location or enclosure has been compromised (potentially affected)
The device is affected if it is a TEW-827DRU running firmware 2.08B01 with physically accessible UART headers and insufficient physical security controls.
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.
From vendor dataApply physical security controls to prevent unauthorized access to device circuit boards and UART headers; contact vendor for firmware update addressing UART authentication.
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20161 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
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-2021-20161 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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- 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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