CVE-2026-36784: Shenzhen Tenda Technology Co

Synopsis

A stack-based buffer overflow in the Tenda O3 Wireless Router (firmware v1.0.0.5(4180)) allows a remote attacker to crash the device by sending a crafted HTTP request with an oversized value in the ip parameter of the fromNetToolGet function. No authentication is required and no user interaction is needed, making the device reachable by any attacker who can send it an HTTP request. Successful exploitation causes a Denial of Service, taking the router offline until it is manually restarted. No fix version has been published; HarborGuard tracks the upstream advisory and will make a patched-image rebuild available as soon as one is released.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

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

• AuthenticationNot required

  No credentials are needed; the vulnerable fromNetToolGet endpoint is accessible without logging in.

• Victim interactionNot required

  The attacker sends a single crafted HTTP request with no user action required on the target device.

• Attack complexityDetail

  Exploitation is reliable and condition-free; no race conditions or special environmental factors are required to trigger the overflow.

Blast Radius

• The router process crashes, dropping all network traffic routed through the device until it is manually restarted.
• Any connected devices that depend on the router for internet or LAN connectivity lose network access for the duration of the outage.
• Repeated exploitation can maintain a persistent denial-of-service state, preventing administrators from regaining connectivity through the affected device.