A critical stack-based buffer overflow in Tenda AC7 firmware allows authenticated attackers to execute arbitrary code or cause system crashes.

The vulnerability exists in the /goform/fast_setting_pppoe_set endpoint, where an attacker-supplied password is saved and subsequently retrieved by the /goform/fast_setting_get interface into a fixed-size stack buffer without boundary validation. While the CVSS vector indicates a requirement for low privileges (PR:L), the flaw permits a remote attacker to trigger memory corruption.

Successful exploitation of this vulnerability can lead to a complete compromise of the affected router, resulting in unauthorized access to network traffic, interception of credentials, or total loss of device availability. Given the CVSS score of 8.8, this represents a high-severity risk to network infrastructure. Compromised edge devices can serve as persistent entry points for lateral movement into internal segments, creating significant operational and security risks.

Immediate Action: Users should immediately check the Tenda support portal for firmware updates and apply the latest version available for the AC7 model. If no patch is available, restrict management interface access to trusted administrative networks only.

Proactive Monitoring: Security teams should monitor network traffic for anomalous POST requests directed at the /goform/fast_setting_pppoe_set endpoint. Review device logs for unexpected crashes or reboot patterns that may indicate failed or successful exploitation attempts.

Compensating Controls: Implement strict firewall rules to prevent unauthorized or external access to the device management interface. Ensure that the router is not exposed directly to the public internet.

Public Exploit Available: Yes, a published proof-of-concept exists as documented in the referenced security researcher write-up.

The presence of a public proof-of-concept combined with the potential for remote code execution makes this a high-priority remediation item. Network administrators must prioritize patching affected Tenda AC7 devices or isolating them from untrusted network segments immediately to prevent potential exploitation.