CVE-2026-36793: Shenzhen Tenda Technology Co

Synopsis

Multiple stack-based buffer overflows exist in the Tenda W3 Wireless Router (firmware v1.0.0.3(2204)) within the formwrlSSIDset function, triggered by oversized values in the mit_ssid and mis_ssid_index HTTP request parameters. The vulnerability is reachable over the network with no authentication required and no user interaction needed. Successful exploitation crashes the router, causing a denial of service. HarborGuard is tracking this advisory and will make a patched-image rebuild available the moment an upstream fix is published.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the router's HTTP service over the network; no local or physical access is required.

• AuthenticationNot required

  No account or credential is needed to send the malicious HTTP request to the vulnerable endpoint.

• Victim interactionNot required

  The exploit is fully attacker-driven and requires no action from any user of the device.

• Attack complexityDetail

  Exploitation is reliable and condition-free; the attacker only needs to craft an HTTP request with an oversized parameter value.

Blast Radius

• Crashes the router's management process, taking the device offline and cutting network connectivity for all clients behind it.
• Repeated exploitation keeps the device in a denial-of-service loop until it is power-cycled or replaced.
• Any dependent network services (DHCP, DNS forwarding, internet access) become unavailable for the duration of the attack.