CVE-2026-51602 describes a stack-based buffer overflow in the RTSP service of Tenda CP3 V3.0 firmware V31.1.9.91. The vulnerability arises because the second-stage URL routing parser does not properly validate the length of the URL field in the first SETUP request. By sending a URL composed of four consecutive repetitions of a valid RTSP URL, an attacker bypasses first-stage format validation and triggers a stack buffer overflow. This causes an immediate crash of the RTSP service process, resulting in denial of service and loss of device accessibility on the local network. The attack requires no authentication and targets the RTSP service specifically.

The vulnerability allows an unauthenticated remote attacker to cause a denial of service by crashing the RTSP service on affected devices. This results in the device becoming inaccessible to all clients on the local network relying on the RTSP service. There is no information about code execution or data compromise, only service disruption.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or workaround information is provided at this time. Until a patch is available, restricting access to the RTSP service from untrusted networks or disabling the RTSP service if not required may reduce exposure.