CVE-2025-67186
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 · uneditedTOTOLINK A950RG V4.1.2cu.5204_B20210112 contains a buffer overflow vulnerability in the setUrlFilterRules interface of /lib/cste_modules/firewall.so. The vulnerability occurs because the `url` parameter is not properly validated for length, allowing remote attackers to trigger a buffer overflow, potentially leading to arbitrary code execution or denial of service.
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 setUrlFilterRules function of the firewall.so library in TOTOLINK A950RG router firmware V4.1.2cu.5204_B20210112. The vulnerability is caused by insufficient length validation on the url parameter, allowing remote attackers to overflow a 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= 4.1.2cu.5204_b20210112CVSS 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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Check router firmware versionAccess the router's web management interface (typically at 192.168.1.1) and navigate to System Status or Firmware Version page. Alternatively, check via CLI if telnet/ssh is enabled: 'cat /proc/version' or 'nvram get firm_version'Affected if The installed firmware version is exactly 4.1.2cu.5204_B20210112
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Verify firewall.so library presenceIf you have shell access to the router (via telnet/ssh), check for the existence of the firewall library: 'ls -la /lib/firewall.so' or 'find / -name firewall.so'Affected if The firewall.so library exists on the device, indicating the vulnerable component is present
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Confirm URL filter feature is accessibleIn the router web interface, locate the URL Filtering or Website Filter feature under Security or Access Control settings. Check if this feature is visible and configurableAffected if The URL filtering feature is present and accessible in the router's management interface (this feature invokes the vulnerable setUrlFilterRules function)
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Check for unauthorized configuration changesIf you have access to router logs or configuration backups, examine the URL filter rules configuration for unusually long URL strings that may indicate exploitation attemptsAffected if The URL filter configuration contains excessively long URL entries that exceed normal length limits
A user is affected if their TOTOLINK A950RG router runs firmware version 4.1.2cu.5204_B20210112 and the URL filtering feature in firewall.so is accessible.
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 patch when available; in the interim, restrict network access to the router's management interface using firewall rules and implement network segmentation to limit exposure to remote attackers.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-67186 — 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-2025-67186 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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