A critical stack-based buffer overflow in Tenda CX12L routers could allow an attacker on the local network to execute arbitrary code or cause a denial of service.

This is a stack-based buffer overflow vulnerability residing in the fromwebExcptypemanFilter function within the /goform/webExcptypemanFilter endpoint. The vulnerability is triggered when the application fails to perform bounds checking on the page parameter before copying it into a fixed-size buffer, allowing a local network attacker to manipulate memory and execution flow.

Successful exploitation of this vulnerability poses a severe risk to organizational network security. An attacker capable of reaching the device via the local network could gain full control over the router, potentially leading to unauthorized monitoring of sensitive traffic, lateral movement into internal systems, or complete denial of service for network infrastructure. The CVSS score of 8.0 reflects the high potential for system compromise and the impact on availability and integrity.

Immediate Action: Since a specific patch is not currently available, administrators should restrict access to the web management interface to trusted administrative IP addresses only. If the device is not critical, consider isolating it from the main network until a firmware update is provided by Tenda.

Proactive Monitoring: Review device system logs for unexpected reboots or crashes, which may indicate attempted exploitation. Monitor network traffic for unusual POST requests directed at the /goform/webExcptypemanFilter endpoint.

Compensating Controls: Implement network segmentation to ensure the management interface of the router is not accessible from untrusted segments. Deploy a firewall or Intrusion Prevention System (IPS) rule to drop POST requests that contain abnormally large payloads in the page parameter.

Public Exploit Available: Yes, a published proof-of-concept exists as documented in the researcher's GitHub issue referenced by the CVE record.

Given the availability of a functional proof-of-concept and the potential for arbitrary code execution, this vulnerability represents a significant threat to network integrity. Organizations utilizing the Tenda CX12L router should treat this as a high-priority issue. Apply the recommended compensating controls immediately and monitor vendor support channels for the release of a security-hardened firmware version.