A critical stack-based buffer overflow vulnerability in the Tenda F456 router allows authenticated remote attackers to achieve remote code execution.

The flaw resides in the fromVirtualSer function within the httpd component, where the page parameter is copied into a stack-based buffer without sufficient length validation. This vulnerability requires the attacker to be authenticated with low privileges to trigger the overflow through a crafted HTTP POST request.

The ability to execute arbitrary code on networking equipment poses a severe risk to organizational security, as it grants attackers a foothold to intercept traffic, pivot into internal network segments, or disrupt critical connectivity. With a CVSS score of 8.8, this vulnerability is classified as High severity, reflecting the potential for total system compromise. Successful exploitation could lead to unauthorized access to sensitive data and significant operational downtime for users relying on the affected hardware.

Immediate Action: Since a specific patch version is not currently available, administrators should restrict network access to the management interface of the Tenda F456 to trusted administrative IP addresses only.

Proactive Monitoring: Security teams should monitor network traffic for suspicious POST requests targeting the /goform/VirtualSer endpoint, particularly those containing unusually long string parameters.

Compensating Controls: Implement Web Application Firewall (WAF) rules or network-level access control lists (ACLs) to filter traffic and block malformed requests directed at the vulnerable router interface.

Public Exploit Available: Yes — a published proof-of-concept exists, as documented in the security researcher's technical write-up on GitHub.

Given the availability of a public proof-of-concept and the potential for remote code execution, this vulnerability represents a significant threat to internal infrastructure. Organizations should immediately isolate the management interfaces of affected Tenda F456 devices and monitor for vendor updates to address this memory corruption flaw as soon as they become available.