A critical stack-based buffer overflow in D-Link DIR-816 routers enables remote code execution, posing an immediate risk of full device compromise.

This vulnerability is a stack-based buffer overflow occurring within the goahead component's handling of the form2Wl5RepeaterStep2.cgi file. An unauthenticated remote attacker can trigger this condition by supplying malicious input to the key1, key2, key3, key4, or pskValue arguments.

Successful exploitation of this vulnerability allows for remote code execution, which could result in complete loss of device control, unauthorized network access, and potential lateral movement into internal systems. Given the CVSS score of 9.8, this represents a critical risk that could lead to significant operational disruption and data breach.

Immediate Action: As the affected product is end-of-life and no patch is available, the primary remediation is to retire the device and replace it with a supported alternative.

Proactive Monitoring: Monitor network traffic for unusual POST requests directed toward the /goform/form2Wl5RepeaterStep2.cgi endpoint.

Compensating Controls: Implement strict firewall rules to prevent external access to the administrative interface of the router.

Public Exploit Available: Yes

Due to the critical nature of this vulnerability and the lack of vendor-supplied patches, we strongly recommend the immediate decommissioning of affected D-Link DIR-816 units. If replacement is not immediately feasible, ensure the device is isolated from the public internet using robust perimeter security controls.