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

The vulnerability exists within the fromSafeUrlFilter function of the /goform/SafeUrlFilter endpoint in the httpd component. By sending a crafted HTTP POST request with an overly long page parameter, a low-privileged attacker can trigger a memory corruption event, leading to potential remote code execution.

Successful exploitation of this vulnerability poses a severe threat to network integrity, as it allows unauthorized remote code execution on the affected router. This could result in full device compromise, enabling attackers to intercept traffic, pivot into the internal network, or permanently disable critical connectivity infrastructure. With a CVSS score of 8.8, this flaw represents a high-risk entry point that requires immediate attention to prevent unauthorized access to the network perimeter.

Immediate Action: Contact Tenda support or check the official vendor portal for firmware updates addressing this buffer overflow, as no official patch version is currently identified. If an update is unavailable, restrict access to the web management interface to trusted internal segments only.

Proactive Monitoring: Monitor network traffic for anomalous HTTP POST requests directed at the /goform/SafeUrlFilter endpoint. Review device logs for unexpected crashes or service restarts that may indicate successful or attempted exploitation.

Compensating Controls: Implement a Web Application Firewall (WAF) or an Intrusion Prevention System (IPS) rule to inspect and block excessively large POST payloads directed at the vulnerable URL path.

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

Given the availability of a public proof-of-concept and the high-impact nature of remote code execution, this vulnerability poses a significant risk to network security. Administrators should prioritize securing the web management interface of the Tenda F456 and monitor for any vendor-issued firmware updates to permanently resolve the underlying memory corruption flaw.