A critical stack-based buffer overflow vulnerability in Tenda O3 firmware allows remote attackers to cause memory corruption and potential system compromise.

The vulnerability exists within the SetValue and GetValue functions of the /goform/setVlanConfig endpoint, where the lan parameter is processed without sufficient length or content validation. An authenticated attacker can supply an oversized input that, when later retrieved and stored on the stack, results in a buffer overflow.

This vulnerability poses a significant risk to network infrastructure, as successful exploitation leads to memory corruption and potential execution of arbitrary code on the affected device. Given the CVSS score of 8.8, this flaw represents a high risk of total loss of device integrity and potential lateral movement within the network. Organizations relying on these devices for connectivity may face service disruptions and unauthorized access to internal management interfaces.

Immediate Action: As no patch is currently available, restrict access to the web management interface of the Tenda O3 device to trusted management networks only.

Proactive Monitoring: Review device logs for unusual POST requests directed at the /goform/setVlanConfig or /goform/getVlanConfig endpoints.

Compensating Controls: Deploy a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to monitor and block traffic containing unusually large payloads within the lan parameter.

Public Exploit Available: Yes, a published proof-of-concept exists as documented in the linked research write-up on GitHub.

Given the availability of a public proof-of-concept and the potential for remote code execution, this vulnerability should be treated with high urgency. Administrators must implement strict network access controls to isolate affected devices from external access until the vendor releases a firmware update that introduces proper input validation.