CVE-2026-6156
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 vulnerability has been detected in Totolink A7100RU 7.4cu.2313_b20191024. This affects the function setIpQosRules of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. The manipulation of the argument Comment leads to os command injection. Remote exploitation of the attack is possible. The exploit has been disclosed publicly 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 A7100RU router firmware 7.4cu.2313_b20191024. The setIpQosRules function in /cgi-bin/cstecgi.cgi fails to sanitize the Comment argument before passing it to system shell, allowing remote attackers to execute arbitrary 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 modelCheck the router's web interface, label, or SNMP/sysinfo for model number Totolink A7100RUAffected if Device is not a Totolink A7100RU router (different models are not affected by this specific CVE)
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Check firmware versionAccess router web UI (typically at 192.168.0.1 or 192.168.1.1), navigate to Status or System section, or run 'ubus call system info' via SSH if available, and locate firmware version 7.4cu.2313_b20191024Affected if Firmware version matches or predates 7.4cu.2313_b20191024 (vulnerable code likely present in this and earlier builds)
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Verify vulnerable CGI endpoint existsCheck if /cgi-bin/cstecgi.cgi is accessible on the device by attempting to access it via HTTP/HTTPS (e.g., curl http://ROUTER_IP/cgi-bin/cstecgi.cgi)Affected if The CGI binary responds (even with an error) indicating the endpoint is present and potentially exploitable
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Confirm remote management is enabledIn router web UI, check WAN access settings under Administration, Remote Management, or similar. Look for options like 'Enable Remote Management' or 'Allow WAN Access' that expose the CGI interface to the internetAffected if Remote management/WAN access to the web interface is enabled, allowing external attackers to reach the vulnerable CGI endpoint
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Inspect QoS rule configuration accessIn router web UI, navigate to QoS, Bandwidth Control, or Traffic Management settings where setIpQosRules function would be called. The vulnerability triggers when saving QoS rules with a malicious Comment fieldAffected if QoS configuration feature is accessible (either locally or remotely), meaning an attacker could inject commands via the Comment parameter
User is affected if they have a Totolink A7100RU router running firmware 7.4cu.2313_b20191024 or earlier, with the vulnerable /cgi-bin/cstecgi.cgi endpoint accessible either locally or remotely.
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 update if available; otherwise restrict administrative interface to trusted networks or disable remote management to reduce attack surface.
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-6156 — 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-2026-6156 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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