Tenda F456 Remote Buffer Overflow Vulnerability

A critical buffer overflow vulnerability, identified as CVE-2026-7078, affects Tenda F456 router firmware version 1.0.0.5. The vulnerability resides in the fromSetIpBind function within the /goform/SetIpBind file, part of the httpd component. A remote attacker can exploit this vulnerability by crafting a malicious HTTP request with a manipulated page argument, leading to arbitrary code execution on the device. The public availability of this exploit increases the risk of widespread exploitation and potential compromise of vulnerable Tenda F456 routers. This is critical for defenders to address because successful exploitation gives attackers full control of the router.

Attack Chain

1. The attacker identifies a vulnerable Tenda F456 router with firmware version 1.0.0.5 exposed to the internet.
2. The attacker crafts a malicious HTTP GET or POST request targeting the /goform/SetIpBind endpoint.
3. Within the request, the attacker includes a specially crafted page argument designed to trigger the buffer overflow in the fromSetIpBind function.
4. The httpd component processes the request without proper bounds checking on the page argument.
5. The oversized page argument overwrites adjacent memory regions in the stack, including the return address.
6. The fromSetIpBind function attempts to return, but the overwritten return address redirects execution to attacker-controlled code.
7. The attacker-controlled code executes with the privileges of the httpd process, typically root.
8. The attacker gains complete control over the device, enabling them to modify settings, intercept traffic, or use the router as a botnet node.

Impact

Successful exploitation of this buffer overflow vulnerability allows a remote attacker to gain complete control over the affected Tenda F456 router. This could lead to unauthorized access to the local network, data theft, or the use of the router as a botnet node. Given the ease of exploitation and the public availability of the exploit, a large number of devices could be compromised if left unpatched. This could lead to large-scale DDoS attacks or widespread data breaches.

Recommendation

• Monitor web server logs for requests to /goform/SetIpBind with abnormally long page parameters, which could indicate exploitation attempts (see the provided Sigma rule).
• Implement rate limiting on requests to /goform/SetIpBind to reduce the impact of potential exploitation attempts.
• Consider deploying a web application firewall (WAF) rule to filter out malicious requests targeting the /goform/SetIpBind endpoint.
• Apply any available patches or firmware updates released by Tenda to address CVE-2026-7078.