A critical buffer overflow vulnerability in Tenda TX9 routers, specifically in the SetStaticRouteCfg function, permits remote attackers to execute arbitrary code or cause a denial of service.

The vulnerability exists in the sub_42D03C function, which fails to perform bounds checking on the user-provided list parameter before copying it into a stack-based buffer. While the CVSS vector indicates low privileges are required, the flaw allows remote exploitation via the /goform/SetStaticRouteCfg endpoint.

Successful exploitation of this buffer overflow can result in full system compromise or a permanent denial of service. Given the CVSS score of 8.8, this vulnerability represents a high risk to network availability and data confidentiality, particularly for organizations relying on these devices for secure perimeter or internal network routing.

Immediate Action: There is currently no vendor-supplied patch; users should restrict access to the web management interface of the Tenda TX9 device to trusted management networks only.

Proactive Monitoring: Monitor device logs and network traffic for unusual POST requests directed at the /goform/SetStaticRouteCfg endpoint, specifically looking for abnormally long string parameters.

Compensating Controls: Deploy a Web Application Firewall or an Intrusion Prevention System with custom rules to drop HTTP requests containing excessively long payloads in the list parameter.

Public Exploit Available: Yes, a functional proof-of-concept exploit is publicly available via a researcher's GitHub repository.

Due to the availability of a public proof-of-concept and the high severity of memory corruption flaws, organizations must treat this vulnerability with urgency. If the vendor does not release a firmware update, consider replacing or isolating the affected hardware to prevent remote unauthorized access to the network infrastructure.