A critical stack-based buffer overflow vulnerability in Tenda F456 firmware version 1.0.0.5 poses a significant risk of remote code execution.

The flaw exists within the fromNatlimit function of the httpd service, where a user-provided page parameter is passed to sprintf without proper length validation. An authenticated attacker can trigger this memory corruption by sending a crafted HTTP POST request to the /goform/Natlimit endpoint.

Successful exploitation of this vulnerability allows an attacker to achieve remote code execution on the affected device, potentially leading to a complete compromise of the router. Given the CVSS score of 8.8, the risk of unauthorized system access and persistent network control is severe, which may result in lateral movement within the local network or interception of sensitive traffic.

Immediate Action: As no official patch is currently available, administrators should restrict network access to the management interface of the F456 device to trusted internal segments only.

Proactive Monitoring: Monitor device logs for unusual POST requests directed at the /goform/Natlimit endpoint and look for unexpected service restarts or abnormal system behavior.

Compensating Controls: Implement strict firewall rules to block unauthorized access to the web-based management interface, effectively preventing remote exploitation attempts.

Public Exploit Available: Yes — a published proof-of-concept exists in the researcher write-up linked in the CVE references.

The severity of this vulnerability, combined with the availability of a public proof-of-concept, necessitates immediate action. Administrators must isolate the vulnerable hardware from the public internet and apply vendor-supplied firmware updates as soon as they become available to remediate the underlying buffer overflow flaw.