A heap-based buffer overflow vulnerability in Tenda M3 routers allows remote attackers to achieve memory corruption, posing a severe risk to device integrity.

The vulnerability exists in the formSetVlanPolicy function within the /goform/setVlanPolicyData endpoint. An attacker with low-level privileges can trigger a heap-based buffer overflow by providing a maliciously crafted value for the qvlan_truck_port parameter.

The exploitation of this memory corruption vulnerability can lead to a total loss of system availability or potential remote code execution, depending on the memory layout. Given the CVSS score of 8.8, this flaw represents a high risk to business operations, as compromised networking equipment can serve as an entry point for lateral movement or the interception of internal network traffic.

Immediate Action: Users should update their Tenda M3 firmware to a patched version if available, or restrict access to the web management interface to trusted administrative networks only.

Proactive Monitoring: Security teams should monitor network traffic for POST requests to the /goform/setVlanPolicyData endpoint containing unusually long strings within the qvlan_truck_port parameter.

Compensating Controls: Implement a Web Application Firewall (WAF) or an Intrusion Prevention System (IPS) rule to inspect and block excessively large inputs sent to the setVlanPolicyData form.

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

Due to the availability of a public proof-of-concept and the high severity of heap-based memory corruption, organizations utilizing Tenda M3 devices must treat this vulnerability with high urgency. Administrators should verify the current firmware version and apply the manufacturer's security updates immediately to prevent unauthorized access or system instability.