A critical stack-based buffer overflow vulnerability in Tenda AC500 firmware permits remote code execution, posing a significant risk of full system compromise.

The vulnerability resides in the formSetAPCfg function within the /goform/setWtpData endpoint, where the radio_2g_1 parameter is copied into a stack-based buffer without sufficient length validation. This memory corruption flaw can be triggered by a logged-in (authenticated) user to execute arbitrary code or crash the device.

The ability for a remote attacker to execute arbitrary code on networking hardware presents a severe business risk, including the potential for complete network interception, lateral movement into internal systems, and persistent device control. With a CVSS score of 8.8, this vulnerability is categorized as High, reflecting the potential for total loss of confidentiality, integrity, and availability of the affected device.

Immediate Action: As no official patch is currently identified, administrators should restrict access to the device management interface to trusted IP addresses only and disable remote management features where possible.

Proactive Monitoring: Monitor system logs for repeated crashes or unusual POST requests directed at the /goform/setWtpData endpoint, which may indicate exploitation attempts.

Compensating Controls: Implement a Web Application Firewall (WAF) or network-level access control list (ACL) to filter or block malicious payloads containing excessively long strings in the radio_2g_1 parameter.

Public Exploit Available: Yes, a functional proof-of-concept exploit is available via the researcher's published write-up on GitHub.

Given the availability of a public proof-of-concept and the high potential for remote code execution, this vulnerability represents a severe threat to network infrastructure. Organizations using the Tenda AC500 should immediately restrict network exposure of the device interface and actively seek guidance from the vendor regarding firmware updates to address this memory corruption defect.