CVE-2026-51606
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 · uneditedAn improper input handling vulnerability in the RTSP service of Tenda CP3 V3.0 (firmware V31.1.9.91) causes the device to abruptly terminate the TCP connection with a RST packet when a request containing an oversized field value is received, without returning any RFC 2326-compliant error response. This behavior affects the request-line URL field and header field values across multiple RTSP request types.
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 confidenceThe Tenda CP3 V3.0 RTSP service fails to properly handle oversized field values in request-line URLs and header fields. Instead of returning RFC 2326-compliant error responses (e.g., 400 Bad Request), the device abruptly terminates the TCP connection with a RST packet, causing a denial of service condition for legitimate clients and revealing information about the service's input handling limitations.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Confirm device is Tenda CP3 V3.0Access the device's web interface or check the device label/metadata to verify the exact model and firmware version. Look for 'CP3' and version 'V3.0' specifically.Affected if The device is not a Tenda CP3 V3.0 unit
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Verify RTSP service is enabledCheck the device's web interface under Services or Security settings for RTSP/RTSP Server configuration. Confirm RTSP is turned on. Default RTSP port is 554.Affected if RTSP service is disabled on the device
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Confirm RTSP port is accessibleFrom an external client, run 'nc -zv <device_ip> 554' or 'telnet <device_ip> 554' to verify the RTSP port is reachable and accepting connections.Affected if RTSP port 554 is not reachable or filtered
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Test oversized request-line URL handlingSend an RTSP request with an abnormally long request-line URL (e.g., GET / followed by thousands of characters) using a tool like netcat or a custom script. Observe the response.Affected if Connection is terminated with TCP RST packet instead of returning a 400 Bad Request response
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Test oversized header field handlingSend an RTSP request with oversized header field values (e.g., a User-Agent header with thousands of characters). Observe how the server responds.Affected if Connection is terminated with TCP RST packet instead of returning a 400 Bad Request response
The device is affected if it is a Tenda CP3 V3.0 with RTSP enabled, and sending oversized request-line URLs or header fields causes TCP RST termination rather than RFC-compliant 400 error responses.
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 dataUpdate to a patched firmware version that implements proper input validation and returns RFC-compliant error responses instead of connection resets. If no update is available, restrict RTSP service access to trusted networks via firewall rules.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-51606 — 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-2026-51606 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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