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Command InjectionWeakness · CWE-77

CVE-2026-7140

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability has been found in Totolink A8000RU 7.1cu.643_b20200521. Impacted is the function CsteSystem of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. Such manipulation of the argument HTTP leads to os command injection. The attack may be performed from remote. The exploit has been disclosed to the public 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 · moderate confidence

OS command injection vulnerability in Totolink A8000RU router's /cgi-bin/cstecgi.cgi CGI handler. The CsteSystem function fails to properly sanitize the HTTP argument, allowing remote attackers to execute arbitrary OS commands. The vulnerability is remotely exploitable and a public exploit exists.

MitigationApply vendor firmware patch when available; until then, disable remote administration interfaces or restrict access to trusted IPs only to reduce attack surface.

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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device model is Totolink A8000RU
    Access the router admin interface or check the device label/model number. Alternatively, inspect HTTP responses from the router for Totolink branding or check the WAN IP reverse DNS.
    Affected if Device is a Totolink A8000RU router (no version range provided, treat all versions as potentially affected)
  2. Verify CGI endpoint /cgi-bin/cstecgi.cgi is accessible
    Send an HTTP request to the router's IP at path /cgi-bin/cstecgi.cgi. Use curl or a browser to test: curl -s http://<router-ip>/cgi-bin/cstecgi.cgi
    Affected if The CGI endpoint responds (status 200 or similar), indicating the vulnerable handler is present and reachable
  3. Check if remote administration is enabled
    Log into the router admin panel and navigate to System > Remote Management or similar. Alternatively, probe port 80/443 from an external IP to confirm the web interface is reachable from WAN.
    Affected if Remote administration (HTTP/HTTPS from WAN) is enabled on the router, making the vulnerability remotely exploitable
  4. Look for signs of command injection compromise
    Review router system logs for unexpected commands, new user accounts, or unfamiliar processes. Check for modified configuration files or unexpected network connections using 'netstat' on the router if shell access is available.
    Affected if Logs show unexpected OS commands, new administrative accounts, or indicators of unauthorized access consistent with command injection
  5. Check for the presence of the public exploit
    Search for CVE-2026-7140 or Totolink A8000RU exploits in security databases. If a compromise is suspected, examine network traffic for patterns matching known PoC code targeting cstecgi.cgi.
    Affected if Exploit code matching this CVE is found in use against the environment or present on systems that could target this router

The environment is affected if the Totolink A8000RU router has its /cgi-bin/cstecgi.cgi CGI handler accessible, particularly from remote networks, as the CsteSystem function allows command injection through unsanitized HTTP arguments.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor firmware patch when available; until then, disable remote administration interfaces or restrict access to trusted IPs only to reduce attack surface.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
38.0 hours of engineering $6,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-7140 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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