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Improper AuthenticationWeakness · CWE-287

CVE-2026-5676

HIGH · 7.3 CVSS v3.1 Published 2026-04-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
82/100
Remediation priority · High
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 A8000R 5.9c.681_B20180413. This issue affects the function setLanguageCfg of the file /cgi-bin/cstecgi.cgi. Such manipulation of the argument langType leads to missing authentication. The attack can be launched 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 · moderate confidence

Missing authentication vulnerability in Totolink A8000R router's web interface (cgi-bin/cstecgi.cgi). The setLanguageCfg function can be accessed without authentication by manipulating the langType parameter, allowing remote unauthenticated attackers to potentially access or modify router settings.

MitigationApply available vendor firmware updates; if no patch exists, restrict administrative interface access to trusted networks or disable remote management.

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
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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 the device model
    Access the router web interface or check the device label/marketing to confirm it is a Totolink A8000R router
    Affected if The device is not a Totolink A8000R (different models may have different vulnerabilities)
  2. Check the firmware version
    Log into the router web interface and navigate to System Status or Firmware Upgrade page to view the current firmware version. Alternatively, check via SSH/Telnet if available using 'cat /proc/version' or '固件版本' command
    Affected if The firmware version is 5.9c.681_B20180413 or earlier (the specific version mentioned in the advisory)
  3. Verify web management accessibility
    Check the router settings under 'Remote Management' or 'Administration' to see if 'Web Management' or 'HTTP/HTTPS Management' is enabled for WAN/remote access. Attempt to access http://<WAN_IP>/cgi-bin/cstecgi.cgi from an untrusted network to confirm external accessibility
    Affected if The router web interface (cgi-bin/cstecgi.cgi) is accessible from untrusted networks (WAN) rather than only from the local LAN
  4. Confirm the CGI endpoint exists
    Access the URL http://<router_IP>/cgi-bin/cstecgi.cgi via browser or curl and observe the response. A 200 OK or JSON response indicates the endpoint is active
    Affected if The cgi-bin/cstecgi.cgi endpoint is reachable and responds to requests (this is required for the vulnerable function to be accessible)
  5. Test for authentication bypass on setLanguageCfg
    Send a POST request to /cgi-bin/cstecgi.cgi with a JSON payload such as {'topicurl':'setLanguageCfg','langType':'en'} without including any session cookies or authentication headers. Use: curl -X POST http://<router_IP>/cgi-bin/cstecgi.cgi -H 'Content-Type: application/json' -d '{"topicurl":"setLanguageCfg","langType":"en"}'
    Affected if The request returns a successful response (not a login redirect or 401/403 error) indicating the function is accessible without authentication

The device is affected if it is a Totolink A8000R router running firmware version 5.9c.681_B20180413 or earlier, the web interface is accessible remotely, and the setLanguageCfg CGI function responds without requiring authentication credentials.

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 available vendor firmware updates; if no patch exists, restrict administrative interface access to trusted networks or disable remote management.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,820
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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-2026-5676 in production — separate from our analysis above.

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What belongs here
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