Tenda F456 Remote Buffer Overflow Vulnerability

A critical buffer overflow vulnerability, identified as CVE-2026-7098, has been discovered in Tenda F456 router version 1.0.0.5. The vulnerability resides within the fromDhcpListClient function of the /goform/DhcpListClient component’s httpd service. An attacker can exploit this flaw by remotely manipulating the page argument, leading to a buffer overflow. Publicly available exploit code exists, increasing the risk of widespread exploitation. Successful exploitation could allow an attacker to execute arbitrary code on the device, potentially gaining full control of the router and the network it serves. This poses a significant threat to home and small business users relying on these routers.

Attack Chain

1. Attacker identifies a vulnerable Tenda F456 router (version 1.0.0.5) accessible over the network.
2. The attacker crafts a malicious HTTP request targeting the /goform/DhcpListClient endpoint.
3. The crafted request includes a page argument with a payload designed to overflow the buffer in the fromDhcpListClient function.
4. The httpd service processes the request and calls the fromDhcpListClient function.
5. Due to insufficient bounds checking, the oversized payload overwrites the buffer, potentially overwriting adjacent memory regions.
6. The attacker’s payload overwrites the return address on the stack with a pointer to attacker-controlled code.
7. The fromDhcpListClient function returns, causing execution to jump to the attacker-controlled code.
8. The attacker-controlled code executes with the privileges of the httpd service, potentially allowing for full control of the device.

Impact

Successful exploitation of this vulnerability can allow a remote attacker to execute arbitrary code on the Tenda F456 router. This could lead to a complete compromise of the device, allowing the attacker to modify router settings, intercept network traffic, or use the router as a pivot point for further attacks within the network. Given the ease of exploitation and public availability of exploit code, a large number of Tenda F456 users are at risk.

Recommendation

• Monitor web server logs for suspicious requests to /goform/DhcpListClient with unusually long page parameters to detect potential exploitation attempts (see Sigma rule “Detect Tenda F456 Buffer Overflow Attempt”).
• Implement rate limiting on requests to the /goform/DhcpListClient endpoint to mitigate the impact of potential attacks.
• Deploy the Sigma rule “Detect Tenda F456 Buffer Overflow Response” to identify successful exploitation attempts based on server response codes.