Tenda F456 Router Buffer Overflow Vulnerability

hello@craftedsignal.io — Mon, 27 Apr 2026 04:16:09 +0000

A critical buffer overflow vulnerability, identified as CVE-2026-7081, affects Tenda F456 router version 1.0.0.5. The vulnerability resides in the fromGstDhcpSetSer function within the /goform/GstDhcpSetSer file, a component of the device’s httpd service. Successful exploitation allows a remote attacker to execute arbitrary code on the device. Publicly available exploit code increases the risk of widespread exploitation. This vulnerability poses a significant threat as it can lead to complete compromise of the affected device, potentially allowing attackers to gain unauthorized access to the network, steal sensitive information, or use the device as part of a botnet.

Attack Chain

The attacker identifies a vulnerable Tenda F456 router (version 1.0.0.5) exposed to the internet.
The attacker crafts a malicious HTTP POST request targeting the /goform/GstDhcpSetSer endpoint.
The HTTP request includes the dips argument, which is intentionally oversized to trigger the buffer overflow.
The vulnerable fromGstDhcpSetSer function processes the request without proper bounds checking.
The oversized dips argument overwrites adjacent memory regions on the stack.
The attacker carefully crafts the overflow to overwrite the return address with an address pointing to attacker-controlled code.
The fromGstDhcpSetSer function returns, causing execution to jump to the attacker’s code.
The attacker’s code executes with the privileges of the httpd process, potentially leading to full device compromise.

Impact

Successful exploitation of this vulnerability allows a remote attacker to execute arbitrary code on the affected Tenda F456 router. This can result in complete device compromise, including the ability to modify device settings, intercept network traffic, and potentially use the compromised device as a pivot point for further attacks within the network. Given the widespread use of Tenda routers, a large number of devices could be vulnerable, making this a significant security concern.

Recommendation

Monitor web server logs for suspicious POST requests to /goform/GstDhcpSetSer with unusually long dips parameter values to detect potential exploitation attempts.
Deploy the provided Sigma rule Detect Tenda F456 Buffer Overflow Attempt to identify malicious HTTP requests.
Since no patch is available, consider replacing the affected Tenda F456 routers (version 1.0.0.5) with more secure alternatives.

Tenda F456 Remote Buffer Overflow Vulnerability

hello@craftedsignal.io — Tue, 02 Jan 2024 12:00:00 +0000

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

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

F456 — CraftedSignal Threat Feed

Tenda F456 Router Buffer Overflow Vulnerability

Attack Chain

Impact

Recommendation

Tenda F456 Remote Buffer Overflow Vulnerability

Attack Chain

Impact

Recommendation