CVE-2018-21156
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 · uneditedCertain NETGEAR devices are affected by a buffer overflow by an authenticated user. This affects D6220 before 1.0.0.38, D6400 before 1.0.0.74, D7000v2 before 1.0.0.74, D8500 before 1.0.3.39, DGN2200v4 before 1.0.0.102, DGN2200Bv4 before 1.0.0.102, EX3700 before 1.0.0.70, EX3800 before 1.0.0.70, EX6000 before 1.0.0.30, EX6100 before 1.0.2.22, EX6120 before 1.0.0.40, EX6130 before 1.0.0.22, EX6150 before 1.0.0.38, EX6200 before 1.0.3.86, EX7000 before 1.0.0.64, R6250 before 1.0.4.20, R6300v2 before 1.0.4.22, R6400 before 1.0.1.32, R6400v2 before 1.0.2.52, R6700 before 1.0.1.44, R6900 before 1.0.1.44, R6900P before 1.3.0.18, R7000 before 1.0.9.28, R7000P before 1.3.0.18, R7300DST before 1.0.0.62, R7900 before 1.0.2.10, R7900P before 1.3.0.10, R8000 before 1.0.4.12, R8000P before 1.3.0.10, R8300 before 1.0.2.116, R8500 before 1.0.2.116, WN2500RPv2 before 1.0.1.52, WNDR3400v3 before 1.0.1.18, and WNR3500Lv2 before 1.2.0.46.
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 confidenceThis CVE describes a buffer overflow vulnerability in multiple NETGEAR router and range extender models that can be exploited by an authenticated user. The vulnerability exists in the web management interface and allows privilege escalation or denial of service. Affected devices span multiple product lines (D, R, EX, WNDR, WNR series) with specific firmware version thresholds for each model.
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< 1.0.0.38< 1.0.0.74< 1.0.0.74< 1.0.3.39< 1.0.0.102< 1.0.0.102< 1.0.0.70< 1.0.0.70CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/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 your NETGEAR device modelLocate the model number label on the device or access the web management interface and look for the model identifier typically displayed on the status or administration pageAffected if The device model is one of: D6220, D6400, D7000, D8500, Dgn2200, Dgn2200b, Ex3700, Ex3800
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Check the installed firmware versionLog into the web management interface, navigate to the Router Status or Administration > Firmware Upgrade page, and record the firmware version displayedAffected if The firmware version cannot be determined or is not visible in the interface
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Compare firmware version against affected thresholdsMatch your device model and firmware version to the following thresholds: D6220 < 1.0.0.38, D6400 < 1.0.0.74, D7000 < 1.0.0.74, D8500 < 1.0.3.39, Dgn2200 < 1.0.0.102, Dgn2200b < 1.0.0.102, Ex3700 < 1.0.0.70, Ex3800 < 1.0.0.70Affected if Your installed firmware version is lower than the threshold listed for your specific model
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Verify web management interface accessibilityConfirm that the web management interface (HTTP/HTTPS on ports 80 or 443) is accessible from your network by attempting to reach the router's IP address in a browserAffected if The web interface is accessible and you have confirmed an affected firmware version below the threshold
You are affected if you have a NETGEAR device from the listed models running firmware version lower than the specified threshold for that model.
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 data1.0.0.381.0.0.701.0.0.74
Apply the corresponding firmware update for each affected device model as listed in the advisory (e.g., R7000 to version 1.0.9.28 or later). Ensure device administration interfaces are not exposed to untrusted networks to reduce attack surface.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-21156 — 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-2018-21156 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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