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N300rh FirmwareOperating system · Totolink

CVE-2025-4850

MEDIUM · 6.3 CVSS v3.1 Published 2025-05-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Remotely reachable 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 classified as critical has been found in TOTOLINK N300RH 6.1c.1390_B20191101. This affects the function setUnloadUserData of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument plugin_name leads to command injection. It is possible to initiate the attack remotely. 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 · high confidence

Command injection vulnerability in TOTOLINK N300RH router firmware 6.1c.1390_B20191101. The /cgi-bin/cstecgi.cgi CGI binary's setUnloadUserData function fails to sanitize the plugin_name argument, allowing arbitrary command execution with the web server's privileges. Attack is exploitable remotely via HTTP request.

MitigationApply vendor firmware patch if available; if no patch exists, disable or block access to the affected CGI endpoint via firewall rules, or replace the end-of-life device.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
N300rh FirmwareOperating system
Affected:= 6.1c.1390_b20191101

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/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. Confirm device is a TOTOLINK N300RH router
    Access the router web interface or check the device label/model number to verify the model is TOTOLINK N300RH
    Affected if Device is not a TOTOLINK N300RH router - not affected
  2. Check the installed firmware version
    Log into the router admin panel and navigate to the firmware version/status page, or use the command 'cat /proc/version' or 'cat /etc/version' via telnet/SSH if available
    Affected if Firmware version is NOT exactly 6.1c.1390_b20191101 - not affected
  3. Verify the CGI binary exists on the device
    Attempt to access http://<router_ip>/cgi-bin/cstecgi.cgi via HTTP request, or check for the file via telnet/SSH at /usr/sbin/cstecgi or similar paths
    Affected if The /cgi-bin/cstecgi.cgi endpoint does not exist - not affected
  4. Check if the web interface is accessible
    Attempt an HTTP connection to the router's IP address on port 80 or 443
    Affected if The router web interface is not reachable remotely - the remote attack vector is not applicable

A user is affected only if they have a TOTOLINK N300RH router running exactly firmware version 6.1c.1390_b20191101 with the web interface accessible.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor firmware patch if available; if no patch exists, disable or block access to the affected CGI endpoint via firewall rules, or replace the end-of-life device.

Recommended fix Moderate confidence

Latest N300RH firmware available from www.totolink.net (newer than 6.1c.1390_B20191101)

  1. 1. Visit the official TOTOLINK support page at www.totolink.net and navigate to the N300RH product support section.
  2. 2. Download the latest available firmware version for the N300RH router.
  3. 3. Access the router's web administration interface (typically at 192.168.0.1 or 192.168.1.1).
  4. 4. Navigate to the Firmware Upgrade or System Tools section.
  5. 5. Upload and apply the new firmware file.
  6. 6. After the upgrade completes, verify the firmware version in the router's status page.
  7. 7. Confirm the vulnerability is resolved by checking that the /cgi-bin/cstecgi.cgi endpoint no longer accepts command injection via the plugin_name parameter.
Caveat Firmware upgrades may reset router configuration to defaults; backup current settings before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in N300rh Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2025-4850 in production — separate from our analysis above.

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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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