CVE-2020-27866
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 · uneditedThis vulnerability allows network-adjacent attackers to bypass authentication on affected installations of NETGEAR R6020, R6080, R6120, R6220, R6260, R6700v2, R6800, R6900v2, R7450, JNR3210, WNR2020, Nighthawk AC2100, and Nighthawk AC2400 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the mini_httpd service, which listens on TCP port 80 by default. The issue results from incorrect string matching logic when accessing protected pages. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of root. Was ZDI-CAN-11355.
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 confidenceAuthentication bypass vulnerability in the mini_httpd web server (TCP port 80) on multiple NETGEAR router models. The flaw stems from incorrect string matching logic when accessing protected pages, allowing unauthenticated network-adjacent attackers to bypass authentication. Can be chained with other vulnerabilities for root-level code execution.
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< 1.2.0.76< 1.2.0.76< 1.2.0.76< 1.2.0.76< 1.2.0.76< 1.2.0.76< 1.2.0.76< 1.2.0.76CVSS 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 router modelLocate the model number on the router device label or access the router web interface and check the status or administration page for the model nameAffected if Router model matches any of: Ac2100, Ac2400, Ac2600, R6700, R6800, R6900, R7200, R7350
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Check installed firmware versionAccess the router web interface at http://192.168.1.1 (default), navigate to Administration > Firmware Update or Router Status page, and record the firmware version displayedAffected if Firmware version is lower than 1.2.0.76 for the identified model
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Confirm mini_httpd service is runningAttempt to access the router web interface on TCP port 80 from a network-connected device. Use a browser to navigate to the router IP address and observe if the login page loadsAffected if Web interface responds on port 80 and is accessible from the network segment
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Verify if remote administration is enabledIn the router web interface, go to Advanced > Remote Management or Administration > Remote Management settings. Check if remote management access is enabled for LAN or WANAffected if Remote administration is enabled, allowing network-adjacent attackers to reach the web interface
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Compare version against affected rangeDocument the exact firmware version string from step 2 and compare numerically against version 1.2.0.76, noting that any version below this threshold is affectedAffected if Installed firmware version is 1.2.0.75 or lower, or any version string that compares less than 1.2.0.76
The router is affected if it is one of the listed Netgear models (Ac2100, Ac2400, Ac2600, R6700, R6800, R6900, R7200, R7350) AND the installed firmware version is below 1.2.0.76 AND the mini_httpd web interface on port 80 is network-accessible.
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 data1.2.0.76
Apply vendor-supplied firmware updates for affected router models. If no update is available, restrict network access to the router's management interface via firewall rules or disable remote administration.
- Consultation4.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-27866 — 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-2020-27866 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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