CVE-2026-36794: Shenzhen Tenda Technology Co

Synopsis

Stack-based buffer overflows in the Tenda W3 Wireless Router (firmware v1.0.0.3(2204)) allow an unauthenticated remote attacker to crash the device by sending a crafted HTTP request to the R7WebsSecurityHandler function via the username or password parameters. No authentication or victim interaction is needed; the attacker only needs network access to the router's web interface. Successful exploitation causes a denial of service, taking the device offline. 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 vulnerable HTTP endpoint is exposed over the network, so the attacker must be able to reach the router's web interface to send the crafted request.

• AuthenticationNot required

  No credentials are needed; the overflow is triggered through the login parameters before any authentication check completes.

• Victim interactionNot required

  The attack is fully automated and requires no action from any user on the targeted device.

• Attack complexityDetail

  Exploitation is reliable and condition-free; the attacker simply sends an oversized value in the username or password field of a crafted HTTP request.

Blast Radius

• Crashes the router's web-facing process, rendering the device unresponsive and dropping all network connectivity for clients behind it.
• Repeated requests can sustain the outage, effectively bricking network access for the affected segment until the device is manually rebooted.
• No confidentiality or integrity impact is indicated; the attacker gains no data access or ability to modify configuration.