A3300r FirmwareOperating system · Totolink

CVE-2026-5176

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-31
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
Public exploit 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 security flaw has been discovered in Totolink A3300R 17.0.0cu.557_b20221024. Affected is the function setSyslogCfg of the file /cgi-bin/cstecgi.cgi. Performing a manipulation of the argument provided results in command injection. The attack may be initiated remotely. The exploit has been released to the public and may 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

A command injection vulnerability exists in Totolink A3300R router firmware 17.0.0cu.557_b20221024 within the setSyslogCfg function of /cgi-bin/cstecgi.cgi. The function fails to properly sanitize user input, allowing an attacker to inject and execute arbitrary operating system commands remotely.

MitigationApply vendor firmware patch if available; otherwise disable remote management interfaces, implement network segmentation, or replace affected devices. If continued use is required, restrict access to the management interface via firewall rules.

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
A3300r FirmwareOperating system
Affected:= 17.0.0cu.557_b20221024

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 A3300R
    Access the router web interface and check the device model information, or check the device label. Alternatively, inspect the HTTP responses from the router which may reveal the model in headers or login pages.
    Affected if The device is not a Totolink A3300R router - this vulnerability does not apply to other models.
  2. Identify the installed 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 the footer or status page of the web interface for version information.
    Affected if The installed firmware version is exactly 17.0.0cu.557_b20221024 - this is the only version listed as affected by this CVE.
  3. Check if /cgi-bin/cstecgi.cgi is present and accessible
    Attempt to access https://<router-ip>/cgi-bin/cstecgi.cgi via HTTP OPTIONS request or by analyzing available CGI endpoints on the device. This file contains the vulnerable setSyslogCfg function.
    Affected if The CGI binary exists and responds to requests - the vulnerable function is present in this version.
  4. Verify the setSyslogCfg function is exposed
    Send a crafted request to the CGI endpoint with the setSyslogCfg action parameter to confirm the function exists. This typically involves a POST request with the function name.
    Affected if The function responds without error - the command injection point is available for exploitation.

You are affected if you are running a Totolink A3300R router with firmware version 17.0.0cu.557_b20221024 and the web interface is accessible to an attacker.

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 disable remote management interfaces, implement network segmentation, or replace affected devices. If continued use is required, restrict access to the management interface via firewall rules.

Fix this in A3300r Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2026-5176 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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