CVE-2026-1638
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 · uneditedA security flaw has been discovered in Tenda AC21 1.1.1.1/1.dmzip/16.03.08.16. The impacted element is the function mDMZSetCfg of the file /goform/mDMZSetCfg. The manipulation of the argument dmzIp results in command injection. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.
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 confidenceA command injection vulnerability exists in Tenda AC21 firmware version 1.1.1.1 (16.03.08.16) in the mDMZSetCfg function within /goform/mDMZSetCfg. The dmzIp parameter is not properly sanitized before being passed to system command execution, allowing an authenticated remote attacker to inject arbitrary shell commands.
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= 16.03.08.16CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 model and firmware versionLog into the Tenda AC21 admin interface (typically at 192.168.0.1) and navigate to System Settings > Firmware Version, or check the label on the device itselfAffected if The firmware version is exactly 16.03.08.16 (displayed as 1.1.1.1)
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Verify the DMZ feature is accessibleNavigate to the router's NAT/Firewall settings and check if the DMZ configuration page (mDMZ or DMZ settings) is present and accessible in the web interfaceAffected if The DMZ configuration interface exists and is enabled or configurable on the device
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Confirm remote management is enabled (optional attack surface)Check the router's System Settings > Remote Management or Access Control settings to see if WAN-side administrative access is permittedAffected if Remote management/Remote access from WAN is enabled, allowing unauthenticated or authenticated access from the internet
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Check for command injection evidenceIf you have access to the router's diagnostics or command execution logs, review them for suspicious commands involving the dmzIp parameter in /goform/mDMZSetCfgAffected if Unexpected shell commands or system() calls appear in logs referencing the DMZ configuration function
You are affected if you are running Tenda AC21 firmware version 16.03.08.16 (1.1.1.1) and the DMZ feature is accessible on your router.
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 patch when available. As an interim control, disable the router's remote management interface from WAN-facing networks and restrict administrative access to trusted IP addresses only.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-1638 — 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-2026-1638 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
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