CVE-2018-21203
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 stack-based buffer overflow by an unauthenticated attacker. This affects R6100 before 1.0.1.20, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.96, WNDR4300 before 1.0.2.98, WNDR4300v2 before 1.0.0.50, and WNDR4500v3 before 1.0.0.50.
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 · moderate confidenceA stack-based buffer overflow vulnerability exists in multiple NETGEAR router models (R6100, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, WNDR4500v3). The flaw can be exploited by an unauthenticated remote attacker, potentially allowing arbitrary code execution or device compromise.
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< 1.0.1.20< 1.0.2.52< 1.0.2.96< 1.0.2.98< 1.0.0.50< 1.0.0.50CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/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 router modelCheck the product label on the device or log into the router admin interface (typically at 192.168.1.1) and look for the model number in the status or device info pageAffected if The model is one of: R6100, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, or WNDR4500v3
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Check the installed firmware versionIn the router admin interface, navigate to Administration > Firmware Update or Advanced > Administration > Router Update and note the current firmware version displayedAffected if The firmware version is lower than: 1.0.1.20 for R6100, 1.0.2.52 for R9000, 1.0.2.96 for WNDR3700, 1.0.2.98 or 1.0.0.50 for WNDR4300, or 1.0.0.50 for WNDR4500v3
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Verify network exposure of the routerCheck if the router management interface (HTTP/HTTPS on ports 80/443) is accessible from outside your local network, or check port forwarding/NAT rules that may expose the admin interfaceAffected if The router admin interface is reachable from untrusted networks (internet or guest Wi-Fi) without VPN or firewall protection
You are affected if you own one of the listed Netgear models AND your firmware version is below the patched version AND the router is network-accessible to potential attackers.
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 data1.0.0.501.0.1.201.0.2.52
Apply the vendor-supplied firmware updates: R6100 to 1.0.1.20+, R9000 to 1.0.2.52+, WNDR3700v4 to 1.0.2.96+, WNDR4300 to 1.0.2.98+, and WNDR4300v2/WNDR4500v3 to 1.0.0.50+. If updates are unavailable, restrict network access to these devices.
- Consultation4.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2018-21203 — 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-2018-21203 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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