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Command InjectionWeakness · CWE-77

CVE-2026-6155

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-13
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 weakness has been identified in Totolink A7100RU 7.4cu.2313. The impacted element is the function setWanCfg of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. Executing a manipulation of the argument pppoeServiceName can lead to os command injection. The attack may be launched remotely. The exploit has been made available to the public and could 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 confidence

OS command injection vulnerability in Totolink A7100RU router firmware 7.4cu.2313. The pppoeServiceName parameter in the setWanCfg function of /cgi-bin/cstecgi.cgi lacks proper input sanitization, allowing attackers to inject arbitrary OS commands through the CGI handler.

MitigationApply vendor firmware patch when available; until then, disable remote management interfaces from untrusted networks or implement network-level access controls to block external access to the vulnerable CGI endpoint.

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. Identify firmware version
    Access router admin panel or check firmware file; look for version string '7.4cu.2313' in system information or boot logs
    Affected if Running Totolink A7100RU firmware version 7.4cu.2313 exactly
  2. Verify CGI binary exists
    Check if /cgi-bin/cstecgi.cgi exists on the device (via firmware extraction or admin panel file browser if available)
    Affected if The file /cgi-bin/cstecgi.cgi is present on the device
  3. Confirm remote management is exposed
    Check router firewall settings; determine if admin interface or CGI endpoint is reachable from WAN IP address on ports 80/443/8080
    Affected if Remote administration or the CGI endpoint is accessible from untrusted networks (WAN side)
  4. Identify WAN connection type
    Check router WAN settings; look for PPPoE connection type configuration
    Affected if PPPoE is configured as the WAN connection type, making the pppoeServiceName parameter relevant

You are affected if you are running Totolink A7100RU firmware 7.4cu.2313 with PPPoE WAN and the CGI endpoint is accessible remotely.

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 management interfaces from untrusted networks or implement network-level access controls to block external access to the vulnerable CGI endpoint.

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-2026-6155 in production — separate from our analysis above.

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What this is

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