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Stack-based Buffer OverflowWeakness · CWE-121

CVE-2026-51602

HIGH · 7.5 CVSS v3.1 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click 6 weeks old

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 stack-based buffer overflow vulnerability in the RTSP service of Tenda CP3 V3.0 (firmware V31.1.9.91) allows an unauthenticated remote attacker to cause a denial of service via a crafted SETUP request. The RTSP service's second-stage URL routing parser fails to validate the length of the URL field in the first SETUP request. By supplying a URL consisting of exactly four consecutive repetitions of a valid RTSP URL, an attacker can bypass first-stage format validation and trigger a stack buffer overflow, causing an immediate crash of the RTSP service process and rendering the device inaccessible to all clients on the local network.

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

Stack-based buffer overflow in Tenda CP3 V3.0 RTSP service. The second-stage URL routing parser does not validate URL length in the first SETUP request. By sending a URL with exactly four consecutive repetitions of a valid RTSP URL, an attacker bypasses first-stage format validation and overflows a stack buffer, crashing the RTSP service and rendering the device inaccessible.

MitigationApply vendor firmware patch when available. As interim mitigation, restrict network access to the RTSP service using firewall rules or network segmentation to prevent unauthenticated attackers from reaching the device.

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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm device model and firmware version
    Access the device web interface or check the device label to identify the exact model (Tenda CP3) and firmware version (V3.0). Compare against the affected product.
    Affected if Device is Tenda CP3 running firmware version 3.0 or other unpatched versions in the V3.0 line
  2. Verify RTSP service is enabled
    Log into the device administration panel and check the RTSP service settings. Typically found under 'Advanced' or 'Camera' settings. Confirm RTSP is turned ON.
    Affected if RTSP service is enabled and running on the device
  3. Check RTSP port accessibility
    Use a network scanner or telnet/nmap to test connectivity to port 554 (default RTSP) from both local network and external/untrusted networks. Example: nc -zv <device_ip> 554
    Affected if Port 554 is open and reachable from an untrusted network segment
  4. Test RTSP service responsiveness
    Send an RTSP OPTIONS request to the device using a tool like FFmpeg or a simple socket test: echo -e 'OPTIONS rtsp://<device_ip>/live/ch00_0 RTSP/1.0 CSeq: 1 ' | nc <device_ip> 554
    Affected if Service does not respond or immediately crashes upon receiving a malformed URL request (indicating potential prior exploitation)
  5. Review RTSP service logs for crashes
    Access device logs through the web interface (typically under 'System' > 'Logs' or 'Maintenance' > 'Log') or check syslog if exported. Look for RTSP service restarts, crashes, or out-of-memory errors.
    Affected if Logs show repeated RTSP service crashes or unexpected restarts

The device is affected if it is a Tenda CP3 with RTSP service enabled, and the RTSP service (port 554) is accessible from a network where untrusted users can send requests to it.

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 when available. As interim mitigation, restrict network access to the RTSP service using firewall rules or network segmentation to prevent unauthenticated attackers from reaching the device.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2026-51602 in production — separate from our analysis above.

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What this is

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What belongs here
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