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Command InjectionWeakness · CWE-77

CVE-2026-7538

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-01
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 was identified in Totolink A8000RU 7.1cu.643_b20200521. This issue affects the function Vulnerability of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. The manipulation of the argument proto leads to os command injection. The attack may be initiated remotely. The exploit is publicly available and might 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 confidence

OS command injection vulnerability in Totolink A8000RU router's CGI handler (/cgi-bin/cstecgi.cgi). The 'proto' parameter is not properly sanitized, allowing remote attackers to inject arbitrary OS commands through the web interface.

MitigationApply vendor firmware patch if available; otherwise isolate device on separate network segment or replace with actively supported hardware. Consider disabling remote web management if not required.

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 web interface or check the device label/marketing materials. The vulnerability applies specifically to the A8000RU model.
    Affected if Device is not a Totolink A8000RU router
  2. Identify the firmware version
    Log into the router web interface and navigate to System Status or Firmware Upgrade page to view the installed firmware version. Alternatively, check via telnet/SSH if available using 'cat /proc/version' or 'nvram get firm_version'.
    Affected if Unable to determine firmware version for comparison
  3. Verify the CGI handler is accessible
    Attempt to access 'http://<router-ip>/cgi-bin/cstecgi.cgi' from a client on the same network. A 403, 404, or valid response indicates the endpoint exists.
    Affected if The CGI endpoint /cgi-bin/cstecgi.cgi is not reachable (may indicate different firmware or disabled web interface)
  4. Check if remote web management is enabled
    In the router web interface, go to Administration > Remote Management (or similar). Look for settings that allow access to the web interface from WAN/external IPs.
    Affected if Remote management (WAN access) is enabled for the web interface, exposing the vulnerable CGI handler to the internet

You are affected if you have a Totolink A8000RU router with an accessible web interface and the vulnerable /cgi-bin/cstecgi.cgi endpoint is reachable, especially if remote management is enabled.

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 if available; otherwise isolate device on separate network segment or replace with actively supported hardware. Consider disabling remote web management if not required.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2026-7538 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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