CVE-2025-12240
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 A3300R 17.0.0cu.557_B20221024. This affects the function setDmzCfg of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument ip leads to buffer overflow. It is possible to initiate the attack remotely. 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 confidenceA buffer overflow vulnerability exists in the TOTOLINK A3300R router firmware (17.0.0cu.557_B20221024) within the /cgi-bin/cstecgi.cgi web interface. The setDmzCfg function fails to properly validate the length of the 'ip' parameter before copying it into a fixed-size buffer, allowing remote attackers to overflow the buffer and potentially execute arbitrary code or cause denial of service.
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= 17.0.0cu.557_b20221024CVSS 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 router modelAccess the router admin interface or check the device label to confirm the model is TOTOLINK A3300RAffected if Model is not A3300R, then not affected by this specific CVE
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Check installed firmware versionLog into the router web interface, navigate to System Status or Firmware Upgrade page, and note the firmware version. Alternatively, use the command 'cat /proc/version' or 'ubootenv_get' via UART if you have console accessAffected if Firmware version is exactly 17.0.0cu.557_B20221024 (exact match per affected versions)
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Verify vulnerable CGI endpoint existsSend an HTTP request to /cgi-bin/cstecgi.cgi on the router's IP address. Example: curl -X POST http://<router-ip>/cgi-bin/cstecgi.cgi -d '{"topicurl":"setDmzCfg"}'Affected if The endpoint responds, indicating the cstecgi.cgi binary with setDmzCfg function is present
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Check if DMZ functionality is configuredLog into the router admin interface and navigate to the DMZ settings page (usually under Advanced or NAT settings). Verify whether any DMZ host IP is configuredAffected if A DMZ host IP address is configured and the ip parameter can be submitted to the setDmzCfg function
The environment is affected only if the router model is TOTOLINK A3300R, the firmware is exactly version 17.0.0cu.557_B20221024, and the setDmzCfg function is accessible (which typically requires the DMZ feature to be reachable in the web interface).
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 the latest vendor firmware patch when available; as an interim measure, disable the DMZ functionality through the router admin interface or restrict access to the web management interface to trusted IPs only.
- Consultation4.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-12240 — 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-2025-12240 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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- Version or environment caveats, and links to real fixes
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