A critical stack-based buffer overflow vulnerability in the Tenda 4G300 router allows authenticated remote attackers to achieve arbitrary code execution.

The vulnerability exists within the sub_427C3C function of the /goform/SafeMacFilter file, where improper validation of the page argument leads to a stack-based buffer overflow. This attack requires the user to have low privileges (authenticated) to access the vulnerable administrative interface.

Successful exploitation of this flaw allows an attacker to execute arbitrary code on the affected router, potentially leading to full device compromise. Given the CVSS score of 8.8, this represents a high-severity risk that could result in unauthorized network access, data interception, or the use of the device as a pivot point for further lateral movement within the internal network.

Immediate Action: Since no official patch is currently available, administrators should immediately restrict access to the web management interface of the Tenda 4G300 to trusted IP addresses only.

Proactive Monitoring: Monitor network traffic for unusual patterns directed at the /goform/SafeMacFilter endpoint and review system logs for signs of repeated crashes or abnormal process behavior.

Compensating Controls: Deploy a Web Application Firewall or similar filtering mechanism to sanitize or block requests containing excessively long strings in the page parameter.

Public Exploit Available: Yes, a published proof-of-concept exists and is attributed to the technical write-up provided in the security references.

Due to the lack of an official patch and the availability of a public proof-of-concept, the risk to Tenda 4G300 deployments is significant. Security teams should prioritize isolating these devices from external access and implementing strict network access controls until the vendor provides a firmware update to resolve the memory corruption flaw.