CVE-2026-7098: Tenda F456 Buffer Overflow Vulnerability

CVE-2026-7098 Overview

A buffer overflow vulnerability has been identified in the Tenda F456 router firmware version 1.0.0.5. The vulnerability exists in the fromDhcpListClient function within the /goform/DhcpListClient endpoint of the httpd component. Improper handling of the page argument allows an attacker to trigger a buffer overflow condition remotely. This vulnerability has been publicly disclosed and exploit details are available.

Critical Impact
Remote attackers can exploit this buffer overflow to potentially execute arbitrary code, crash the device, or gain unauthorized access to the router, compromising the entire network segment.

Affected Products

Tenda F456 Firmware version 1.0.0.5
Tenda F456 Hardware Device

Discovery Timeline

2026-04-27 - CVE-2026-7098 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-7098

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromDhcpListClient function in the Tenda F456 router's httpd service fails to properly validate the length of the page parameter before copying it into a fixed-size buffer. When a malicious request is sent to the /goform/DhcpListClient endpoint with an oversized page argument, the function writes beyond the allocated buffer boundaries, corrupting adjacent memory regions.

The network-accessible nature of this vulnerability makes it particularly dangerous, as attackers can exploit it remotely without requiring physical access to the device. Since the httpd service runs with elevated privileges on the router, successful exploitation could result in complete device compromise.

Root Cause

The root cause lies in insufficient bounds checking in the fromDhcpListClient function. The function accepts user-supplied input through the page parameter and processes it without validating that the input length does not exceed the destination buffer size. This is a classic buffer overflow scenario where the developer failed to implement proper input length validation before memory operations.

Attack Vector

The attack is network-based and can be initiated by any authenticated user with access to the router's management interface. An attacker sends a specially crafted HTTP request to the /goform/DhcpListClient endpoint containing an oversized page parameter. The malicious payload overwrites the return address or other critical data structures on the stack, potentially allowing the attacker to redirect execution flow.

The vulnerability can be exploited to achieve denial of service by crashing the httpd process, or potentially remote code execution if the attacker can craft a payload that properly controls the overwritten memory contents. Technical details and proof-of-concept information are available through the GitHub Vulnerability Documentation and VulDB #359673.

Detection Methods for CVE-2026-7098

Indicators of Compromise

Unusual HTTP POST requests to /goform/DhcpListClient with abnormally large page parameter values
Router crashes or unexpected reboots of the httpd service
Suspicious network traffic patterns targeting port 80/443 on the router management interface
Anomalous process behavior or memory consumption on the affected Tenda F456 device

Detection Strategies

Implement network intrusion detection rules to flag HTTP requests to /goform/DhcpListClient containing oversized parameters
Monitor router logs for httpd service crashes or abnormal restart patterns
Deploy web application firewall rules to inspect and block malformed requests to Tenda router endpoints
Utilize packet capture analysis to identify exploitation attempts with characteristic buffer overflow payloads

Monitoring Recommendations

Enable detailed logging on the Tenda F456 router management interface if available
Configure network monitoring to alert on repeated access attempts to /goform/DhcpListClient
Implement baseline monitoring for router uptime and service availability
Consider deploying a network tap or span port to capture traffic destined for router management interfaces

How to Mitigate CVE-2026-7098

Immediate Actions Required

Restrict access to the router management interface to trusted IP addresses only
Disable remote management access if not required for operations
Place the router management interface on a separate VLAN isolated from general network traffic
Implement strong authentication for any management access
Monitor for firmware updates from Tenda addressing this vulnerability

Patch Information

As of the last update on 2026-04-30, no official patch has been released by Tenda for this vulnerability. Administrators should monitor the Tenda Official Website for security updates and firmware releases. Additional vulnerability information is available through VulDB Submission Reference and the VulDB CTI Report.

Workarounds

Configure firewall rules to block external access to the router's web management interface on ports 80 and 443
Use access control lists (ACLs) to limit management interface access to specific administrator IP addresses
Consider replacing the vulnerable device with a router from a vendor with a more responsive security update process
If remote management is required, implement VPN access as an additional security layer

bash

# Example: Restrict management access using upstream firewall rules
# Block external access to router management interface
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow only trusted management subnet
iptables -I FORWARD -s 192.168.1.0/24 -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s 192.168.1.0/24 -d <ROUTER_IP> -p tcp --dport 443 -j ACCEPT