CVE-2021-27246
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 execute arbitrary code on affected installations of TP-Link Archer A7 AC1750 1.0.15 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of MAC addresses by the tdpServer endpoint. A crafted TCP message can write stack pointers to the stack. An attacker can leverage this vulnerability to execute code in the context of the root user. Was ZDI-CAN-12306.
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 confidenceStack-based buffer overflow in TP-Link Archer A7 AC1750 router tdpServer. The vulnerability allows network-adjacent attackers to send crafted TCP messages with malicious MAC address data that overwrites stack pointers, enabling root-level code execution without authentication.
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= 1.0.15CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/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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Confirm device is TP-Link Archer A7 AC1750Identify the router model through the web interface status page, device label, or network scanning. Look for 'Archer A7' or 'AC1750' in the device identification.Affected if Device is not a TP-Link Archer A7 AC1750 model
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Check firmware version equals 1.0.15Log into the router web interface, navigate to Status or System menu, and record the firmware version displayed. The affected version is specifically 1.0.15.Affected if Firmware version is exactly 1.0.15
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Verify tdpServer is accessibleAttempt to connect to TCP port 20002 on the router IP address (this is the default tdpServer port). Use 'nc -zv [router_ip] 20002' or similar network tool to test connectivity.Affected if TCP port 20002 is open and responding on the router
The device is affected if it is an Archer A7 AC1750 running firmware version 1.0.15 with tdpServer (port 20002) exposed to the attacker.
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 update when available; until then, restrict network access to the router's management interface and disable tdpServer if possible.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27246 — 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-2021-27246 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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