Multiple stack overflows exist in the R7WebsSecurityHandler function of the Tenda W3 router, where the username and password parameters are not properly validated. A crafted HTTP request that supplies maliciously sized credentials can overflow the stack, causing the firmware to crash and the device to reboot or become unresponsive. This results in a denial of service for all users connected to the router and can disrupt network operations until the router is rebooted or replaced. The weakness is a classic buffer overflow.

Shenzhen Tenda Technology Co., Ltd Tenda W3 Wireless Router, firmware version v1.0.0.3(2204). No other product variations or versions are listed. Users running this firmware are potentially impacted.

The CVSS score is 7.5, and the EPSS score is < 1%; the vulnerability is not listed in the CISA KEV catalog. Because the flaw can be triggered by a crafted HTTP request to a public management interface, it does not require elevated privileges or prior access. Attackers can invoke the stack overflow simply by sending a malformed username or password to the R7WebsSecurityHandler endpoint. While no active exploits are currently documented, the potential to render the router unusable presents a significant availability risk to any network relying on the device.