A critical stack-based buffer overflow vulnerability in Tenda CH22 firmware allows remote attackers to execute arbitrary code or crash the system.

The vulnerability exists within the fromAdvSetWan function, which fails to perform adequate length validation on the wanmode and PPPOEPassword parameters. This memory corruption flaw allows a remote attacker with low-level privileges to overflow the stack buffer during parameter handling.

Successful exploitation of this vulnerability can result in full system compromise, including the ability for an attacker to execute arbitrary code with elevated privileges. Given the CVSS score of 8.8, this poses a high risk to business operations, as it could lead to unauthorized network access, data exfiltration, or complete service disruption of the affected networking hardware.

Immediate Action: Contact the vendor or check the official Tenda support portal for firmware updates addressing this buffer overflow. If no patch is currently available, restrict access to the web management interface to trusted internal segments only.

Proactive Monitoring: Monitor network traffic for unusual POST requests directed at the /goform/AdvSetWan endpoint, specifically looking for abnormally long parameter strings. Review system logs for unexpected reboots or service crashes that may indicate an exploitation attempt.

Compensating Controls: Deploy a Web Application Firewall (WAF) or an Intrusion Prevention System (IPS) rule to inspect and block HTTP requests containing oversized payloads in the wanmode field.

Public Exploit Available: Yes, a published proof-of-concept exists, as documented in the technical write-up provided by the vulnerability researcher.

The severity of this vulnerability, combined with the availability of a public proof-of-concept, necessitates immediate attention. Security teams should prioritize restricting access to the device management interface while awaiting an official firmware patch from Tenda. Failure to mitigate this risk leaves the infrastructure vulnerable to remote execution and denial of service attacks.