CVE-2025-9090
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 vulnerability was identified in Tenda AC20 16.03.08.12. Affected is the function websFormDefine of the file /goform/telnet of the component Telnet Service. The manipulation leads to command injection. It is possible to launch 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 confidenceA command injection vulnerability exists in the Tenda AC20 router firmware 16.03.08.12 within the Telnet Service component. The websFormDefine function in /goform/telnet improperly handles user input, allowing attackers to inject arbitrary system commands remotely. The public disclosure and CVSS 9.8 score indicate active exploitation risk.
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= 16.03.08.12CVSS 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 the router modelLog into the router administration interface or check the device label to confirm the model is Tenda AC20Affected if The device is a Tenda AC20 router
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Check the firmware versionAccess the router web interface (typically 192.168.0.1) and navigate to System Settings > Firmware Upgrade, or use the command line and check /etc/version or the output of 'cat /proc/version' via telnet/ssh if availableAffected if The installed firmware version is exactly 16.03.08.12
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Verify if the telnet service is enabledAccess the router admin panel and look for Telnet settings under System Tools or Advanced Settings. Alternatively, attempt to connect to the router on port 23 (telnet port) from an internal host using 'telnet <router_ip>' or 'nc -zv <router_ip> 23'Affected if The telnet service is enabled and accepting connections on the router
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Inspect the vulnerable endpointIf you have shell access (via UART, telnet, or SSH), examine the file /goform/telnet and look for the websFormDefine function handling user input. Check for improper input validation or sanitization in the function codeAffected if The /goform/telnet endpoint exists and the websFormDefine function processes input without proper sanitization
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Check for signs of compromiseReview router logs for suspicious commands, unexpected processes, or unauthorized access attempts. Look for unfamiliar processes via 'ps' command or check /var/log/messages if accessible. Monitor network traffic for unusual outbound connections from the routerAffected if Unexpected commands appear in logs, unfamiliar processes are running, or unauthorized access from external IPs is detected
You are affected if you have a Tenda AC20 router running firmware version 16.03.08.12 with the telnet service enabled, as the command injection vulnerability exists in the /goform/telnet endpoint of this specific version.
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 dataIf an official firmware patch is unavailable, disable the telnet service immediately, restrict management interface access to trusted IPs via firewall rules, and monitor for unauthorized telnet access attempts. Consider network segmentation to limit exposure of the device management interface.
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- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-9090 — 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-2025-9090 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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