CVE-2021-23147
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 · uneditedNetgear Nighthawk R6700 version 1.0.4.120 does not have sufficient protections for the UART console. A malicious actor with physical access to the device is able to connect to the UART port via a serial connection and execute commands as the root user without authentication.
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 confidenceThe Netgear Nighthawk R6700 router firmware version 1.0.4.120 exposes an unprotected UART serial console interface. A physically proximate attacker can connect to the UART pins and obtain an unauthenticated root shell, effectively bypassing all logical security controls by directly accessing the underlying Linux system.
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= 1.0.4.120CVSS 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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Check router firmware versionLog into the router web interface (typically 192.168.1.1) and navigate to Administration > Firmware Update or Advanced > Administration > Router Update to view the currently installed firmware version. Alternatively, access the router via telnet/SSH if enabled and run 'cat /proc/version' or 'nvram get firmver'.Affected if The installed firmware version is exactly 1.0.4.120
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Locate UART header on circuit boardPower off the router and remove the casing. Locate the UART header on the main circuit board - it is typically a 4-pin or 6-pin header near the edge of the board, often labeled 'J1' or 'UART'. Inspect for exposed pins that are easily accessible.Affected if A 4 or 6-pin UART header is visibly present and accessible on the circuit board without requiring desoldering or significant physical manipulation
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Verify UART console accessibilityConnect a USB-to-TTL serial adapter (such as FTDI) to the UART pins (VCC, GND, TX, RX) and use a terminal program (PuTTY, minicom) at 115200 baud 8N1. Power on the router and observe if a serial console provides root login without authentication.Affected if The serial console boots to a root shell prompt without requiring any username or password authentication
A Netgear R6700 router is affected if it runs firmware version 1.0.4.120 AND has an exposed, accessible UART header that provides unauthenticated root console access.
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 vendor firmware updates when released; until then, restrict physical access to the device and consider disabling or sealing the UART header if the device is deployed in accessible locations.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-23147 — 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-2021-23147 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
- No weaponised exploit code, or anything meant to cause harm
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