Tenda F451 Router Stack-Based Buffer Overflow Vulnerability

A critical vulnerability, identified as CVE-2026-5989, affects the Tenda F451 router, specifically version 1.0.0.7. The vulnerability lies within the fromRouteStatic function of the /goform/RouteStatic file. By manipulating the page argument, a remote attacker can trigger a stack-based buffer overflow, potentially leading to arbitrary code execution. Publicly available exploit code exists, increasing the risk of exploitation. This vulnerability poses a significant threat as it allows unauthenticated remote attackers to compromise the router, potentially leading to network disruption, data theft, or use of the device in botnet activities.

Attack Chain

1. The attacker identifies a vulnerable Tenda F451 router (version 1.0.0.7) exposed to the internet.
2. The attacker crafts a malicious HTTP request targeting the /goform/RouteStatic endpoint.
3. The request includes a page argument with a payload designed to overflow the stack buffer in the fromRouteStatic function.
4. The vulnerable fromRouteStatic function processes the malicious page argument without proper bounds checking.
5. The buffer overflow overwrites critical data on the stack, including the return address.
6. Upon function return, control is redirected to the attacker-controlled memory region.
7. The attacker executes arbitrary code injected into the overflowed buffer, such as downloading and executing a reverse shell.
8. The attacker gains remote access to the router, potentially allowing further exploitation or network compromise.

Impact

Successful exploitation of CVE-2026-5989 allows an attacker to gain complete control of the Tenda F451 router. This can lead to a variety of damaging outcomes, including denial-of-service attacks against the local network, interception of network traffic, modification of router settings, and the potential use of the compromised router as a node in a botnet. Given the widespread use of Tenda routers in home and small business environments, a large number of devices could be at risk if this vulnerability is actively exploited.

Recommendation

• Monitor web server logs for requests to /goform/RouteStatic containing abnormally long page arguments, as this is indicative of potential exploit attempts. Deploy the Sigma rule Detect Tenda F451 Exploit Attempt to detect these malicious requests.
• Implement rate limiting on requests to the /goform/RouteStatic endpoint to mitigate potential denial-of-service attacks.
• Since there is no patch available, consider replacing vulnerable Tenda F451 routers with more secure devices from other vendors.