CVE-2026-7121
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 flaw has been found in Totolink A8000RU 7.1cu.643_b20200521. This affects the function setWizardCfg of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. This manipulation of the argument wizard causes os command injection. It is possible to initiate the attack remotely. The exploit has been published and may be used.
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 confidenceOS command injection vulnerability in Totolink A8000RU router firmware 7.1cu.643_b20200521. The setWizardCfg function in /cgi-bin/cstecgi.cgi does not properly sanitize the wizard parameter before passing it to system calls, allowing remote attackers to execute arbitrary operating system commands.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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 device modelAccess router web interface or check device label/metadata to confirm the model is Totolink A8000RUAffected if Device is not a Totolink A8000RU router - this CVE does not apply
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Check firmware versionLogin to router admin panel, navigate to System Status or Firmware Upgrade page to view the installed firmware version. Alternatively, check via command line if you have telnet/ssh access.Affected if Firmware version is 7.1cu.643_b20200521 exactly, or falls within the 7.1cu family without the vendor patch applied
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Verify CGI interface is accessibleAttempt to access http://<router-ip>/cgi-bin/cstecgi.cgi from a browser or curl request to confirm the endpoint respondsAffected if The CGI interface is reachable from an attacker's network location - this is required for remote exploitation
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Check if remote administration is enabledIn router web interface, navigate to Advanced Settings or Administration to see if Remote Management/Remote Administration is enabled and which IP addresses can access itAffected if Remote administration is enabled and allows access from outside the local network, increasing exposure to remote attackers
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Look for signs of compromiseIf you have shell access, run 'ps' to check for unexpected processes, check /tmp and /var directories for suspicious files, review router logs for unusual commands in the cstecgi.cgi logsAffected if Unexpected processes, suspicious files in /tmp, or unauthorized commands in logs indicate possible exploitation
You are affected if you own a Totolink A8000RU router running firmware 7.1cu.643_b20200521 and the CGI interface is network-accessible (especially with remote administration enabled), as the unauthenticated wizard parameter in cstecgi.cgi can be injected with OS commands.
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 if available; otherwise, restrict network access to the CGI interface via firewall rules or disable remote administration to block exploitation of this command injection vulnerability.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-7121 — 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-2026-7121 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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